Merge branch '6.3' into 6.4

* 6.3:
  [Serializer] Fix `@method` annotation
  fix compatibility with Doctrine DBAL 4
  ensure string type with mbstring func overloading enabled
  [HttpKernel] Fix quotes expectations in tests
  [Validator] updated Greek translation
  [Cache][HttpFoundation][Lock] Fix empty username/password for PDO PostgreSQL
  [HttpClient][WebProfilerBundle] Do not generate cURL command when files are uploaded

Author: nicolas-grekas

Store/PdoStore.php

@@ -38,8 +38,8 @@ class PdoStore implements PersistingStoreInterface
     private \PDO $conn;
     private string $dsn;
     private string $driver;
-    private string $username = '';
-    private string $password = '';
+    private ?string $username = null;
+    private ?string $password = null;
     private array $connectionOptions = [];
 
     /**

Store/PostgreSqlStore.php

@@ -28,8 +28,8 @@ class PostgreSqlStore implements BlockingSharedLockStoreInterface, BlockingStore
 {
     private \PDO $conn;
     private string $dsn;
-    private string $username = '';
-    private string $password = '';
+    private ?string $username = null;
+    private ?string $password = null;
     private array $connectionOptions = [];
     private static array $storeRegistry = [];