31606:Added strict type declartion

Author: engcom-Echo

app/code/Magento/Sales/Test/Fixture/InvoiceComment.php

@@ -3,6 +3,8 @@
  * Copyright © Magento, Inc. All rights reserved.
  * See COPYING.txt for license details.
  */
+declare(strict_types=1);
+
 namespace Magento\Sales\Test\Fixture;
 
 use Magento\Framework\DataObject;