YITH WooCommerce Gift Cards Premium 4.22.0

* New: support for WooCommerce 9.7
* Update: YITH plugin framework
* Fix: prevent the display of unsent gift cards in My Account

* New: support for WooCommerce 8.6
* Tweak: improved the Delivery Date calendar
* Update: YITH plugin framework
* Fix: trying to get property 'key' of non-object
* Fix: fixed discount calculation using custom amounts with comma as decimal separator
* Dev: added new parameter to the filter "yith_gift_card_select_amount_values"
* Dev: minor changes

4.9.0