function woo_discount_rules_accepted_taxonomy_for_category_method($taxonomy){
    $taxonomy[] = 'product_type';
    return $taxonomy;
}

add_filter('woo_discount_rules_accepted_taxonomy_for_category', 'woo_discount_rules_accepted_taxonomy_for_category_method', 10);

function woo_discount_rules_load_additional_taxonomy_method($categories, $product_id){
   $taxonomy_to_apply = 'product_type';
    $tags = get_the_terms( $product_id, $taxonomy_to_apply );
    if(isset($tags) && (is_object($tags) || is_array($tags)) && count($tags) > 0) {
        foreach ($tags as $tag){
            $categories[] = $tag->term_id;
        }
    }

    return $categories;
}
add_filter('woo_discount_rules_load_additional_taxonomy', 'woo_discount_rules_load_additional_taxonomy_method', 10, 2);