PHP 8.1 & Latest version of ČSOB eAPI 1.9

BC breaks

• Minimal PHP version is now 8.1
• Enums are now native. Instead of Enum::get(Enum::FOO) use just Enum::FOO
• Major changes is payment processing required by new ČSOB API and 3D Secure 2.2. See ČSOB documentation and related pull request for details.
  • https://github.com/csob/paymentgateway/wiki
  • #59