WooCommerce Smart Coupons 8.20.1

* Tweak: Improved bulk generation, export & import of coupons using Action Scheduler Library
* Removed: Background Process Library
* Update: POT file

* Fix: PHP Warning: date() expects parameter 2 to be long, string given
* Fix: Error message: Uncaught Error: [] operator not supported for strings [Shortcode]
* Fix: PHP Notice: Undefined index while auto-generation of coupon in some cases
* Update: Welcome page CSS

* New: Setting to allow auto-generation of coupons on specified order statuses only
* Fix: Warning: mysqli_free_result(): Couldn't fetch mysqli_result on activation of the plugin
* Update: Enable 'Apply before tax' setting for renewal orders as well [WooCommerce Subscriptions]
* Update: Ignore checking for tax enabled on store while processing 'Apply before tax' setting
* Tweak: Any changes made to Smart Coupons settings will now set the setting to not 'autoload'
* Update: POT file