Merge branch '5.3' into 5.4

* 5.3:
  CS fix
  CS fix
  CS fixes
  Bump Symfony version to 5.3.4
  Update VERSION for 5.3.3
  Update CHANGELOG for 5.3.3
  Bump Symfony version to 5.2.12
  Update VERSION for 5.2.11
  Update CHANGELOG for 5.2.11
  Bump Symfony version to 4.4.27
  Update VERSION for 4.4.26
  Update CONTRIBUTORS for 4.4.26
  Update CHANGELOG for 4.4.26

Author: nicolas-grekas

Tests/GatewayApiTransportTest.php

@@ -22,7 +22,7 @@ final class GatewayApiTransportTest extends TransportTestCase
     /**
      * @return GatewayApiTransport
      */
-    public function createTransport(?HttpClientInterface $client = null): TransportInterface
+    public function createTransport(HttpClientInterface $client = null): TransportInterface
     {
         return new GatewayApiTransport('authtoken', 'Symfony', $client ?? $this->createMock(HttpClientInterface::class));
     }