Merge branch '5.3' into 5.4

* 5.3:
  Remove more dynamic properties
  [Serializer] fix support for unset properties on PHP < 7.4

Author: nicolas-grekas

Internal/AmpBody.php

@@ -26,6 +26,7 @@
 class AmpBody implements RequestBody, InputStream
 {
     private $body;
+    private $info;
     private $onProgress;
     private $offset = 0;
     private $length = -1;

RetryableHttpClient.php

@@ -73,7 +73,7 @@ public function request(string $method, string $url, array $options = []): Respo
                 if ('' !== $context->getInfo('primary_ip')) {
                     $shouldRetry = $this->strategy->shouldRetry($context, null, $exception);
                     if (null === $shouldRetry) {
-                        throw new \LogicException(sprintf('The "%s::shouldRetry()" method must not return null when called with an exception.', \get_class($this->decider)));
+                        throw new \LogicException(sprintf('The "%s::shouldRetry()" method must not return null when called with an exception.', \get_class($this->strategy)));
                     }
 
                     if (false === $shouldRetry) {