[BUGFIX] Drop TransientBackendInterface marker on cache backend

TYPO3 v14 changed TransientBackendInterface from an empty marker
interface to a proper contract with

    set(string $entryIdentifier, mixed \$data, ...): void

That contract is incompatible with the parent Typo3DatabaseBackend's
typed signature

    set(string \$entryIdentifier, string \$data, ...): void

so v14 refuses to load a class that both extends Typo3DatabaseBackend
and implements TransientBackendInterface, fataling with:

  Declaration of TYPO3\CMS\Core\Cache\Backend\Typo3DatabaseBackend::set(...)
  must be compatible with TYPO3\CMS\Core\Cache\Backend\TransientBackendInterface::set(...)

ReverseProxyCacheBackend originally declared the marker so the
configured VariableFrontend would skip serialize()/unserialize() on
the stored URL strings. The optimisation was always minor (we store
short strings), and the marker simply cannot coexist with
Typo3DatabaseBackend on v14. Dropping the interface declaration
returns to the default VariableFrontend behaviour — URLs are
serialised/unserialised transparently — which is functionally
identical and works on both v13 and v14.

Author: davidsteeb

Classes/Cache/Backend/ReverseProxyCacheBackend.php

@@ -19,7 +19,6 @@
 
 use B13\Proxycachemanager\Provider\ProxyProviderInterface;
 use Psr\Log\LoggerAwareTrait;
-use TYPO3\CMS\Core\Cache\Backend\TransientBackendInterface;
 use TYPO3\CMS\Core\Cache\Backend\Typo3DatabaseBackend;
 use TYPO3\CMS\Core\Database\ConnectionPool;
 use TYPO3\CMS\Core\Utility\GeneralUtility;
@@ -29,7 +28,7 @@
  * when removing or flushing, additionally does a HTTP Request
  * of course "setting" works naturally in am already working reverse proxy environment.
  */
-class ReverseProxyCacheBackend extends Typo3DatabaseBackend implements TransientBackendInterface
+class ReverseProxyCacheBackend extends Typo3DatabaseBackend
 {
     use LoggerAwareTrait;
     protected ProxyProviderInterface $reverseProxyProvider;