Remove duplicate header

Author: dunglas

src/GraphQl/Serializer/ItemNormalizer.php

@@ -10,14 +10,6 @@
  */
 
 declare(strict_types=1);
-/*
- * This file is part of the API Platform project.
- *
- * (c) Kévin Dunglas <[email protected]>
- *
- * For the full copyright and license information, please view the LICENSE
- * file that was distributed with this source code.
- */
 
 namespace ApiPlatform\Core\GraphQl\Serializer;