Past the following code in the functions.php file of your child-theme:
function cc_mime_types($mimes) {
$mimes['svg'] = 'image/svg+xml';
return $mimes;
}
add_filter('upload_mimes', 'cc_mime_types');
Source: https://css-tricks.com/snippets/wordpress/allow-svg-through-wordpress-media-uploader/