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

Response/JsonMockResponse.php

@@ -15,6 +15,9 @@
 
 class JsonMockResponse extends MockResponse
 {
+    /**
+     * @param mixed $body Any value that `json_encode()` can serialize
+     */
     public function __construct(mixed $body = [], array $info = [])
     {
         try {