WooCommerce Smart Coupons 8.20.1

* New: Tested up to WooCommerce 6.1.1
* New: Column 'sc_coupon_category' in sample.csv file
* Fix: Shipping validation failing on live shipping method
* Update: Improvement in coupon code generation logic
* Update: POT file

* 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