Merge branch '6.4' into 7.0

* 6.4: (23 commits)
  fix merge
  add missing return type-hints
  fix merge
  explicitly mark nullable parameters as nullable
  fix low deps tests
  [HttpKernel] Fix datacollector caster for reference object property
  [Serializer] Fixing PHP warning in the ObjectNormalizer with MaxDepth enabled
  bug #51578 [Cache] always select database for persistent redis connections
  [Security] Validate that CSRF token in form login is string similar to username/password
  [Serializer] Use explicit nullable type
  [validator] validated Dutch translation
  Improve dutch translations
  [Translation] Skip state=needs-translation entries only when source == target
  [HttpKernel] Ensure controllers are not lazy
  [Validator] Fill in trans-unit id 113: This URL does not contain a TLD.
  [Validator] added missing Polish translation for unit 113
  [Validator] add missing lv translation
  [HttpClient] Let curl handle transfer encoding
  [Messenger] Make Doctrine connection ignore unrelated tables on setup
  [HttpFoundation] Set content-type header in RedirectResponse
  ...

Author: xabbuh

CurlHttpClient.php

@@ -250,9 +250,8 @@ public function request(string $method, string $url, array $options = []): Respo
 
             if (isset($options['normalized_headers']['content-length'][0])) {
                 $curlopts[\CURLOPT_INFILESIZE] = (int) substr($options['normalized_headers']['content-length'][0], \strlen('Content-Length: '));
-            }
-            if (!isset($options['normalized_headers']['transfer-encoding'])) {
-                $curlopts[\CURLOPT_HTTPHEADER][] = 'Transfer-Encoding:'.(isset($curlopts[\CURLOPT_INFILESIZE]) ? '' : ' chunked');
+            } elseif (!isset($options['normalized_headers']['transfer-encoding'])) {
+                $curlopts[\CURLOPT_INFILESIZE] = -1;
             }
 
             if ('POST' !== $method) {