Fix - Ensure that when getting costs refunded for an order item there are no PHP errors in sites running PHP 8.0+
Fix - Improve Background Job Handler compatibility with newer WooCommerce versions while processing a job queue
* Fix - Include products with no costs when sorting products by costs in the products admin screen
* Fix - Replace deprecated `is_ajax()` usages in favor of `wp_doing_ajax()`
* Misc - Require WooCommerce 3.9.4 or higher
* Misc - Hide WooCommerce Analytics error notice on the Reports page
* Misc - Remove legacy woo-includes functions
* Misc - Remove the option to apply costs for previous orders without costs
* Misc - Apply costs for all orders is now available only for stores with at least one order
* Misc - Add tooltips for the cost of goods fields on the product page