Cleaned up some obsolete settings from config/cashier.php.
If you've already published config/cashier.php into your application, your can safely remove order_item_preprocessors from the end of the file.
The option to configure OrderItemPreprocessors was already available in config/cashier_plans.php. These preprocessors allow you to customise the order item right before it's processed into the Order - making it a good place to put in some cool custom metered billing logic.