Fix typo in deleteUser function

extensions/t3o_ldap/Classes/Controller/GdprController.php

@@ -229,7 +229,7 @@ Your TYPO3 website administration team';
             throw $e;
         }
 
-        return $ldap->deleteUser($data['userName']);
+        return $ldap->deleteUser($data['username']);
     }
 
     protected function deleteLocalUser(array $data): void