WooCommerce Smart Coupons 9.18.0

* New: Tested up to WooCommerce 6.1.0 & WordPress 5.8.3
* New: Support for coupon categories under bulk generate, import & export
* Update: Coupon not applying to cart via URL coupon if the URL contains 'add-to-cart'
* Update: Prevent generating coupon codes with profanity
* Update: Replaced use of 'is_ajax' with 'wp_doing_ajax'
* Update: POT file

* Fix: Fatal Error: Uncaught Error: Call to undefined function post_exists()
* Update: POT file

* New: WooCommerce 5.9.0 compatible
* New: Tested upto WordPress 5.8.2
* Fix: Displaying error 'Uncaught Exception: Invalid coupon' under the order admin page > Generated coupons meta box, when a coupon that is auto-generated got deleted
* Fix: Support for wildcard email under Allowed emails during 'Bulk generate' & 'Import coupons'
* Update: POT file