[site-reviews] Add .browser-default to SELECT rating element

/**
 * Site Review v5
 * Add the "browser-default" class to the rating SELECT element to prevent it from being transformed by the Materialize theme
 * @param array $field
 * @return array
 */
add_filter('site-reviews/field/rating', function ($field) {
    $classes = explode(' ', $field['class']);
    $classes[] = 'browser-default';
    $field['class'] = implode(' ', $classes);
    return $field;
});