YITH WooCommerce Stripe Premium 3.29.0

* New: support for WooCommerce 6.0
* Update: YITH plugin framework
* Fix: placeholder in refund reason

New: support for WooCommerce 5.4
Update: YITH plugin framework
Update: Stripe PHP library to 7.85.0
Fix: broken link in capture settings
Fix: added new check before updating CC form fields, in order to avoid interfering with other plugins

* New: support for WooCommerce 5.2
* Update: YITH plugin framework
* Update: Stripe PHP library to 7.75.0
* Fix: trialing subscription failing payment due to setup intent checks
* Fix: change payment token also on cancelled or suspended subscriptions, when setting a new default card
* Fix: save intent_id inside order after correctly processing intent in Stripe Classic mode
* Dev: new filters yith_wcstripe_elements_color and yith_wcstripe_elements_font_size
* Dev: added new filters and parameters to make the Stripe form customizable