YITH WooCommerce Gift Cards Premium 4.22.0

* New: support for WooCommerce 5.9
* Update: YITH plugin framework
* Fix: fixed issue with the values in the minor integration with WC Multi Currency
* Fix: including some strings to the domain
* Fix: Corrected text on thank you page and email when use gift this product feature
* Dev: replaced the ABSPATH by the wp_upload_dir method
* Dev: replacing the option _yith_wcmcs_custom_prices by _ywgc_wcmcs_custom_prices
* Dev: added new filter yith_ywgc_skip_orders_autocomplete
* Dev: added the ID gift-this-product to the Gift this product container
* Dev: changed the "Today" placeholder by "Now" in the delivery date field

* New: support for WordPress 5.8
* New: support for WooCommerce 5.5
* New: added new Help tab in the plugin settings
* Update: YITH plugin framework
* Fix: Allow uppercase in image extension
* Fix: fixed the image upload limit in the popup

* New: support for WooCommerce 5.3
* Update: YITH plugin framework
* Fix: fixed the import of the gift cards with a gift card ID
* Fix: fixed a console error related to the select2
* Dev: minor CSS changes
* Dev: added classes to the gift card details in cart
* Dev: convert the gift card value in my account using WPML
* Dev: added a is_array condition to avoid errors in the credit note generation