Merge branch '6.4' into 7.3

* 6.4:
  register attribute loader arguments in a forward-compatible way
  mark test using a Redis connection as an integration test
  ensure compatibility with Relay extension 0.20.0
  [DependencyInjection] Fix `query_string` env processor for URLs without query string
  [DependencyInjection] Fix state corruption in PhpFileLoader during recursive imports
  [FrameworkBundle] Add missing `useAttributeAsKey` calls
  [DependencyInjection] Fix loose validation in #[Autowire] attribute
  [HttpClient] Fix releasing uploaded stream resources

Author: xabbuh

HttpClientTrait.php

@@ -354,6 +354,7 @@ private static function normalizeBody($body, array &$normalizedHeaders = [])
                     }
                 }
             });
+            $caster = null;
 
             if ('' === $body = http_build_query($body, '', '&')) {
                 return '';