* Update WC compatibility version

* Feature – Declare compatibility with WooCommerce High-Performance Order Storage (HPOS).
* Tweak – Added links to the plugin settings, the documentation page, and to get support, in the plugin list.
* Tweak – Updated plugin author.
* Tweak – Tested compatibility up to WC 7.6.
* Tweak – Tested compatibility up to WP 6.2.
* Dev – Use SASS instead of LESS for generating the CSS styles.
* Dev – Implement the singleton pattern in the main plugin class.
* Dev – Updated the minimum requirements to WC 3.5, WP 4.7, and PHP 5.4.

* Tweak – Display the “Refund via Account Funds” button for orders paid with a different payment gateway only on WC 6.8+.

* Fix: frontend JS script error
* New: Cache for variable products
* New: Advanced product options
* New: Quantity measurement

* New – Important: Bumped minimum required versions.
* Fix – Important: Security improvements.
* Fix – Fixed an issue that prevented long text addons from being validated.