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/