WooCommerce Twilio SMS Notifications 1.19.3

* Fix - Compatibility error when certain other SkyVerge plugins are activated

* Fix - "Translations loaded too early" error
* Misc - Tested up to WooCommerce 10.2
* Misc - Improve escaping and sanitizing in codebase

Misc - Add admin notice to help merchants reverting to the checkout shortcode if the checkout block is used

* Misc - Require PHP 7.4 and WordPress 5.6