YITH WooCommerce Advanced Reviews Premium 2.6.0

* New: support for WordPress 5.7
* New: support for WooCommerce 5.1
* Update: YITH plugin framework
* Dev: improved the get_reviews_stats function
* Dev: added post type check at the moment of delete reviews in backend

* Fix: fixed a problem where the reviews are not displayed

* New: Support for WooCommerce 4.9
* Update: plugin framework