Merge branch '5.4' into 6.0

* 5.4:
  [DependencyInjection] Add `SubscribedService` attribute, deprecate current `ServiceSubscriberTrait` usage
  Use try/finally to restore error handlers
  Allow serializer default context configuration

Author: nicolas-grekas

DeprecationErrorHandler/Deprecation.php

@@ -102,8 +102,11 @@ public function __construct($message, array $trace, $file)
         }
 
         set_error_handler(function () {});
-        $parsedMsg = unserialize($this->message);
-        restore_error_handler();
+        try {
+            $parsedMsg = unserialize($this->message);
+        } finally {
+            restore_error_handler();
+        }
         if ($parsedMsg && isset($parsedMsg['deprecation'])) {
             $this->message = $parsedMsg['deprecation'];
             $this->originClass = $parsedMsg['class'];