magento-engcom#101: file clean-up

Clean up the header of the class to fit with the static-tests.

Author: dmanners

app/code/Magento/Catalog/Model/Product/Attribute/Backend/Sku.php

@@ -3,16 +3,15 @@
  * Copyright © Magento, Inc. All rights reserved.
  * See COPYING.txt for license details.
  */
+namespace Magento\Catalog\Model\Product\Attribute\Backend;
+
+use Magento\Catalog\Model\Product;
 
 /**
  * Catalog product SKU backend attribute model
  *
  * @author     Magento Core Team <[email protected]>
  */
-namespace Magento\Catalog\Model\Product\Attribute\Backend;
-
-use Magento\Catalog\Model\Product;
-
 class Sku extends \Magento\Eav\Model\Entity\Attribute\Backend\AbstractBackend
 {
     /**