WooCommerce Group Coupons 2.6.0

* WordPress 6.0 compatible.
* WooCommerce 6.9 compatible.
* Fixes inline Javascript to eliminate the Remove link for automatically applied coupons might get rendered visibly.

* WordPress 6.0 compatible.
* WooCommerce 6.7 compatible.
* Fixed trailing whitespace in code and texts.
* Fixed code doc format issues.
* Removed unused variables.

* Fixes an issue when Groups is not activated, producing a warning with PHP 7 and a fatal error with PHP 8.
* Fixes plugin entry's Settings link should also offered when Groups is not active, as long as the user has the manage_woocommerce capability.