use plugin for svg (functions method didn't work for me)

wordpress/wp-content/plugins/safe-svg/assets/safe-svg.css

+/**
+ * Fix SVGs not showing correctly as featured images.
+ */
+#postimagediv .inside .svg img {
+    width: 100%;
+}
+
+/**
+ * Fix for Gutenberg not showing featured images correctly.
+ */
+img.components-responsive-wrapper__content[src$=".svg"] {
+    position: relative;
+}
\ No newline at end of file

wordpress/wp-content/plugins/safe-svg/composer.json

+{
+	"name": "darylldoyle/safe-svg",
+	"description": "Enable SVG uploads and sanitize them to stop XML/SVG vulnerabilities in your WordPress website",
+	"type": "wordpress-plugin",
+	"license": "GPL-2.0-or-later",
+	"authors": [
+		{
+			"name": "Daryll Doyle",
+			"homepage": "https://wpsvg.com/"
+		}
+	],
+	"require": {
+		"php": "^5.6 || ^7.0"
+	}
+}

wordpress/wp-content/plugins/safe-svg/includes/safe-svg-attributes.php

+<?php
+
+
+class safe_svg_attributes extends \enshrined\svgSanitize\data\AllowedAttributes {
+
+	/**
+	 * Returns an array of attributes
+	 *
+	 * @return array
+	 */
+	public static function getAttributes() {
+
+		/**
+		 * var  array Attributes that are allowed.
+		 */
+		return apply_filters( 'svg_allowed_attributes', parent::getAttributes() );
+	}
+}
\ No newline at end of file

wordpress/wp-content/plugins/safe-svg/includes/safe-svg-tags.php

+<?php
+
+
+class safe_svg_tags extends \enshrined\svgSanitize\data\AllowedTags {
+
+	/**
+	 * Returns an array of tags
+	 *
+	 * @return array
+	 */
+	public static function getTags() {
+
+		/**
+		 * var  array Tags that are allowed.
+		 */
+		return apply_filters( 'svg_allowed_tags', parent::getTags() );
+	}
+}
\ No newline at end of file

wordpress/wp-content/plugins/safe-svg/languages/safe-svg-da_DK.po

+msgid ""
+msgstr ""
+"MIME-Version: 1.0\n"
+"Content-Type: text/plain; charset=UTF-8\n"
+"Content-Transfer-Encoding: 8bit\n"
+"X-Generator: POEditor.com\n"
+"Project-Id-Version: Safe SVG\n"
+"Language: da\n"
+
+#: safe-svg.php:66
+msgid "Sorry, this file couldn't be sanitized so for security reasons wasn't uploaded"
+msgstr "Beklager, kunne denne fil ikke desinficeres, så af sikkerhedsmæssige årsager ikke er uploadet"
+
+#. Plugin Name of the plugin/theme
+#: 
+msgid "Safe SVG"
+msgstr "Sikker SVG"
+
+#. Plugin URI of the plugin/theme
+#: 
+msgid "https://wordpress.org/plugins/safe-svg/"
+msgstr "https://wordpress.org/plugins/safe-svg/"
+
+#. Description of the plugin/theme
+#: 
+msgid "Allows SVG uploads into Wordpress and sanitizes the SVG before saving it"
+msgstr "Tillader SVG uploads i Wordpress og renser SVG før du gemmer det"
+
+#. Author of the plugin/theme
+#: 
+msgid "Daryll Doyle"
+msgstr "Daryll Doyle"
+
+#. Author URI of the plugin/theme
+#: 
+msgid "http://enshrined.co.uk"
+msgstr "http://enshrined.co.uk"
+

wordpress/wp-content/plugins/safe-svg/languages/safe-svg-de_DE.po

+msgid ""
+msgstr ""
+"MIME-Version: 1.0\n"
+"Content-Type: text/plain; charset=UTF-8\n"
+"Content-Transfer-Encoding: 8bit\n"
+"X-Generator: POEditor.com\n"
+"Project-Id-Version: Safe SVG\n"
+"Language: de\n"
+
+#: safe-svg.php:66
+msgid "Sorry, this file couldn't be sanitized so for security reasons wasn't uploaded"
+msgstr "Leider konnte diese Datei nicht bereinigt, damit aus Sicherheitsgründen nicht hochgeladen wurde sein"
+
+#. Plugin Name of the plugin/theme
+#: 
+msgid "Safe SVG"
+msgstr "Safe SVG"
+
+#. Plugin URI of the plugin/theme
+#: 
+msgid "https://wordpress.org/plugins/safe-svg/"
+msgstr "https://wordpress.org/plugins/safe-svg/"
+
+#. Description of the plugin/theme
+#: 
+msgid "Allows SVG uploads into Wordpress and sanitizes the SVG before saving it"
+msgstr "Ermöglicht SVG Uploads in Wordpress und reinigt die SVG vor dem Speichern"
+
+#. Author of the plugin/theme
+#: 
+msgid "Daryll Doyle"
+msgstr "Daryll Doyle"
+
+#. Author URI of the plugin/theme
+#: 
+msgid "http://enshrined.co.uk"
+msgstr "http://enshrined.co.uk"
+

wordpress/wp-content/plugins/safe-svg/languages/safe-svg-en_GB.po

+msgid ""
+msgstr ""
+"MIME-Version: 1.0\n"
+"Content-Type: text/plain; charset=UTF-8\n"
+"Content-Transfer-Encoding: 8bit\n"
+"X-Generator: POEditor.com\n"
+"Project-Id-Version: Safe SVG\n"
+"Language: en\n"
+
+#: safe-svg.php:66
+msgid "Sorry, this file couldn't be sanitized so for security reasons wasn't uploaded"
+msgstr "Sorry, this file couldn't be sanitized so for security reasons wasn't uploaded "
+
+#. Plugin Name of the plugin/theme
+#: 
+msgid "Safe SVG"
+msgstr "Safe SVG "
+
+#. Plugin URI of the plugin/theme
+#: 
+msgid "https://wordpress.org/plugins/safe-svg/"
+msgstr "https://wordpress.org/plugins/safe-svg/"
+
+#. Description of the plugin/theme
+#: 
+msgid "Allows SVG uploads into Wordpress and sanitizes the SVG before saving it"
+msgstr "Allows SVG uploads into Wordpress and sanitizes the SVG before saving it"
+
+#. Author of the plugin/theme
+#: 
+msgid "Daryll Doyle"
+msgstr "Daryll Doyle"
+
+#. Author URI of the plugin/theme
+#: 
+msgid "http://enshrined.co.uk"
+msgstr "http://enshrined.co.uk"
+

wordpress/wp-content/plugins/safe-svg/languages/safe-svg-es_ES.po

+msgid ""
+msgstr ""
+"MIME-Version: 1.0\n"
+"Content-Type: text/plain; charset=UTF-8\n"
+"Content-Transfer-Encoding: 8bit\n"
+"X-Generator: POEditor.com\n"
+"Project-Id-Version: Safe SVG\n"
+"Language: es\n"
+
+#: safe-svg.php:66
+msgid "Sorry, this file couldn't be sanitized so for security reasons wasn't uploaded"
+msgstr "Lo sentimos, este fichero no pudo ser desinfectados por razones de seguridad no fue subido"
+
+#. Plugin Name of the plugin/theme
+#: 
+msgid "Safe SVG"
+msgstr "SVG Segura"
+
+#. Plugin URI of the plugin/theme
+#: 
+msgid "https://wordpress.org/plugins/safe-svg/"
+msgstr "https://wordpress.org/plugins/safe-svg/"
+
+#. Description of the plugin/theme
+#: 
+msgid "Allows SVG uploads into Wordpress and sanitizes the SVG before saving it"
+msgstr "Permite archivos SVG en Wordpress y desinfecta el SVG antes de guardarlo"
+
+#. Author of the plugin/theme
+#: 
+msgid "Daryll Doyle"
+msgstr "Daryll Doyle"
+
+#. Author URI of the plugin/theme
+#: 
+msgid "http://enshrined.co.uk"
+msgstr "http://enshrined.co.uk"
+

wordpress/wp-content/plugins/safe-svg/languages/safe-svg-fr_FR.po

+msgid ""
+msgstr ""
+"MIME-Version: 1.0\n"
+"Content-Type: text/plain; charset=UTF-8\n"
+"Content-Transfer-Encoding: 8bit\n"
+"X-Generator: POEditor.com\n"
+"Project-Id-Version: Safe SVG\n"
+"Language: fr\n"
+
+#: safe-svg.php:66
+msgid "Sorry, this file couldn't be sanitized so for security reasons wasn't uploaded"
+msgstr "Désolé, ce fichier n'a pas pu être désinfectés pour des raisons de sécurité n'a pas été téléchargé"
+
+#. Plugin Name of the plugin/theme
+#: 
+msgid "Safe SVG"
+msgstr "Safe SVG"
+
+#. Plugin URI of the plugin/theme
+#: 
+msgid "https://wordpress.org/plugins/safe-svg/"
+msgstr "https://wordpress.org/plugins/safe-svg/"
+
+#. Description of the plugin/theme
+#: 
+msgid "Allows SVG uploads into Wordpress and sanitizes the SVG before saving it"
+msgstr "Permet le téléchargement de SVG en Wordpress et assainit le SVG avant de l'enregistrer"
+
+#. Author of the plugin/theme
+#: 
+msgid "Daryll Doyle"
+msgstr "Daryll Doyle"
+
+#. Author URI of the plugin/theme
+#: 
+msgid "http://enshrined.co.uk"
+msgstr "http://enshrined.co.uk"
+

wordpress/wp-content/plugins/safe-svg/languages/safe-svg-nl_NL.po

+msgid ""
+msgstr ""
+"MIME-Version: 1.0\n"
+"Content-Type: text/plain; charset=UTF-8\n"
+"Content-Transfer-Encoding: 8bit\n"
+"X-Generator: POEditor.com\n"
+"Project-Id-Version: Safe SVG\n"
+"Language: nl\n"
+
+#: safe-svg.php:66
+msgid "Sorry, this file couldn't be sanitized so for security reasons wasn't uploaded"
+msgstr "Sorry, dit bestand kan niet worden opgeschoond, zodat om veiligheidsredenen werd niet geupload"
+
+#. Plugin Name of the plugin/theme
+#: 
+msgid "Safe SVG"
+msgstr "Safe SVG"
+
+#. Plugin URI of the plugin/theme
+#: 
+msgid "https://wordpress.org/plugins/safe-svg/"
+msgstr "https://wordpress.org/plugins/safe-svg/"
+
+#. Description of the plugin/theme
+#: 
+msgid "Allows SVG uploads into Wordpress and sanitizes the SVG before saving it"
+msgstr "Hiermee kunnen SVG upload in Wordpress en reinigt de SVG alvorens deze op te slaan"
+
+#. Author of the plugin/theme
+#: 
+msgid "Daryll Doyle"
+msgstr "Daryll Doyle"
+
+#. Author URI of the plugin/theme
+#: 
+msgid "http://enshrined.co.uk"
+msgstr "http://enshrined.co.uk"
+

wordpress/wp-content/plugins/safe-svg/languages/safe-svg-ru_RU.po

+msgid ""
+msgstr ""
+"MIME-Version: 1.0\n"
+"Content-Type: text/plain; charset=UTF-8\n"
+"Content-Transfer-Encoding: 8bit\n"
+"X-Generator: POEditor.com\n"
+"Project-Id-Version: Safe SVG\n"
+"Language: ru\n"
+
+#: safe-svg.php:66
+msgid "Sorry, this file couldn't be sanitized so for security reasons wasn't uploaded"
+msgstr "К сожалению, этот файл не может быть продезинфицировать так по соображениям безопасности не был загружен"
+
+#. Plugin Name of the plugin/theme
+#: 
+msgid "Safe SVG"
+msgstr "Безопасный SVG"
+
+#. Plugin URI of the plugin/theme
+#: 
+msgid "https://wordpress.org/plugins/safe-svg/"
+msgstr "https://wordpress.org/plugins/safe-svg/"
+
+#. Description of the plugin/theme
+#: 
+msgid "Allows SVG uploads into Wordpress and sanitizes the SVG before saving it"
+msgstr "Позволяет SVG добавления в Wordpress и дезинфицирует SVG до его сохранения"
+
+#. Author of the plugin/theme
+#: 
+msgid "Daryll Doyle"
+msgstr "Daryll Doyle"
+
+#. Author URI of the plugin/theme
+#: 
+msgid "http://enshrined.co.uk"
+msgstr "http://enshrined.co.uk"
+

wordpress/wp-content/plugins/safe-svg/languages/safe-svg.pot

+# Copyright (C) 2015 Safe SVG
+# This file is distributed under the same license as the Safe SVG package.
+msgid ""
+msgstr ""
+"Project-Id-Version: Safe SVG 1.0.0\n"
+"Report-Msgid-Bugs-To: https://wordpress.org/support/plugin/safe-svg\n"
+"POT-Creation-Date: 2015-07-04 12:31:03+00:00\n"
+"MIME-Version: 1.0\n"
+"Content-Type: text/plain; charset=UTF-8\n"
+"Content-Transfer-Encoding: 8bit\n"
+"PO-Revision-Date: 2015-MO-DA HO:MI+ZONE\n"
+"Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
+"Language-Team: LANGUAGE <LL@li.org>\n"
+
+#: safe-svg.php:66
+msgid ""
+"Sorry, this file couldn't be sanitized so for security reasons wasn't "
+"uploaded"
+msgstr ""
+
+#. Plugin Name of the plugin/theme
+msgid "Safe SVG"
+msgstr ""
+
+#. Plugin URI of the plugin/theme
+msgid "https://wordpress.org/plugins/safe-svg/"
+msgstr ""
+
+#. Description of the plugin/theme
+msgid ""
+"Allows SVG uploads into Wordpress and sanitizes the SVG before saving it"
+msgstr ""
+
+#. Author of the plugin/theme
+msgid "Daryll Doyle"
+msgstr ""
+
+#. Author URI of the plugin/theme
+msgid "http://enshrined.co.uk"
+msgstr ""

wordpress/wp-content/plugins/safe-svg/lib/composer.json

+{
+    "require": {
+        "enshrined/svg-sanitize": "0.*"
+    }
+}