Fix PHP 8.4 deprecation notice in JMS\SerializerBundle\Debug\DataColl…

…ector::collect method

Debug/DataCollector.php

@@ -42,7 +42,7 @@ public function __construct(
         $this->reset();
     }
 
-    public function collect(Request $request, Response $response, \Throwable $exception = null): void
+    public function collect(Request $request, Response $response, ?\Throwable $exception = null): void
     {
     }