Merge branch '6.3' into 6.4

* 6.3:
  fix #51235 - fix the order of merging of serializationContext and self::CONTEXT_DENORMALIZE
  [HttpClient] Fix Static Code Analyzer issue with JsonMockResponse
  [Messenger] Fix exiting `FailedMessagesRetryCommand`
  [Serializer] Fix reindex normalizedData array in AbstractObjectNormalizer::denormalize()
  [Validator] Fix `File::$extensions`’ PHPDoc
  [Mime] Fix email (de)serialization issues
  [Serializer] Fix parsing XML root node attributes
  fix parsing of payload timestamp to DateTimeImmutable
  Fix routing to multiple fallback transports
  Fix missing stamps in delayed message handling
  [DoctrineBridge] Ignore invalid stores in `LockStoreSchemaListener` raised by `StoreFactory`

Author: nicolas-grekas

Constraints/File.php

@@ -73,7 +73,7 @@ class File extends Constraint
     protected $maxSize;
 
     /**
-     * @param array<string, string|string[]>|string[]|string $extensions
+     * @param array<string|string[]>|string $extensions
      */
     public function __construct(
         array $options = null,