Allow SVG upload in media

allow-svg-upload-media.php

<?php
/**
 * Allow SVG
 */

add_filter('wp_check_filetype_and_ext', function ($data, $file, $filename, $mimes) {
    global $wp_version;
    if ($wp_version !== '4.7.1') {
        return $data;
    }

    $filetype = wp_check_filetype($filename, $mimes);

    return [
        'ext'             => $filetype['ext'],
        'type'            => $filetype['type'],
        'proper_filename' => $data['proper_filename']
    ];
}, 10, 4);

function cc_mime_types($mimes){
    $mimes['svg'] = 'image/svg+xml';
    return $mimes;
}
add_filter('upload_mimes', 'cc_mime_types');

function fix_svg(){
    echo '<style type="text/css">
        .attachment-266x266, .thumbnail img {
             width: 100% !important;
             height: auto !important;
        }
        </style>';
}
add_action('admin_head', 'fix_svg');