YITH Stripe Connect for WooCommerce Premium 2.40.0

New: support for WooCommerce 5.0
Update: YITH Plugin Framework
Update: Spanish translation
Fix: issue when trying to pay order with 0 total
Dev: added new yith_wcstripe_allow_save_different_cards filter

New: support for WooCommerce 4.9
Update: plugin framework
Fix: possible fatal error happening in rare cases when processing payment

* Update: plugin framework
* Tweak: added back \YITH_Stripe_Connect_Frontend::stripe_connect_account_page method as deprecated, to improve compatibility