To load brand taxonomies in rule filter when if is not loads

Ensure brand taxonomies load in rule filters when not initially loaded.

add_filter('advanced_woo_discount_rules_get_custom_taxonomies', function($custom_taxonomies) {
    if (function_exists('get_taxonomies')) {
        $custom_taxonomies = array_merge($custom_taxonomies, array_filter(get_taxonomies(array(
            'name' => 'brands',
            'show_ui' => true,
        ), 'objects'), function ($tax) {
            return !in_array($tax->name, array('product_cat', 'product_tag'));
        }));
    }
    return $custom_taxonomies;
});