Merge pull request #682 from ptmkenny/php8.4

Fix php 8.4 deprecation

closes #686

src/Drupal/DrupalExtension/ServiceContainer/DrupalExtension.php

@@ -39,7 +39,7 @@ class DrupalExtension implements ExtensionInterface
    *
    * @param null|ServiceProcessor $processor
    */
-    public function __construct(ServiceProcessor $processor = null)
+    public function __construct(?ServiceProcessor $processor = null)
     {
         $this->processor = $processor ? : new ServiceProcessor();
     }