ENGCOM-2111: Fix static test failure.

Author: p-bystritsky

app/code/Magento/ConfigurableProduct/Plugin/SalesRule/Model/Rule/Condition/Product.php

@@ -1,4 +1,9 @@
-<?php declare(strict_types=1);
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+declare(strict_types=1);
 
 namespace Magento\ConfigurableProduct\Plugin\SalesRule\Model\Rule\Condition;