WooCommerce Group Coupons 2.12.0

* Fixed errors that could occur when evaluating coupons for the cart and there is no cart object.
* Fixed some code formatting issues.

* WordPress 5.5 compatible.
* WooCommerce 4.7 compatible.
* Requires at least WooCommerce 3.0.
* In future updates, at least WooCommerce 4.0 will be required.
* Minor admin section improvement for visual clarity.

* WordPress 5.5 compatible.
* WooCommerce 4.4 compatible.
* Using a more recent API function to check if coupons are enabled to avoid calls that end up using a deprecated function.