minor #46022 Add missing license header (lyrixx)

This PR was merged into the 6.1 branch.

Discussion
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Add missing license header

| Q             | A
| ------------- | ---
| Branch?       | 6.1
| Bug fix?      | no
| New feature?  | no
| Deprecations? | no
| Tickets       |
| License       | MIT
| Doc PR        |

---

And the last one!

Commits
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61c13ec615 Add missing license header

Author: nicolas-grekas

Tests/Exception/LockedHttpExceptionTest.php

@@ -1,9 +1,17 @@
 <?php
 
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
 namespace Symfony\Component\HttpKernel\Tests\Exception;
 
 use Symfony\Component\HttpKernel\Exception\HttpException;
-use Symfony\Component\HttpKernel\Exception\LengthRequiredHttpException;
 use Symfony\Component\HttpKernel\Exception\LockedHttpException;
 
 class LockedHttpExceptionTest extends HttpExceptionTest