chore(reuse): add missing

Author: astratagem

src/Tenancy/Exceptions/MultisiteOnly.php

@@ -1,5 +1,8 @@
 <?php
 
+// SPDX-FileCopyrightText: (C) 2025 Temple University <kleinweb@temple.edu>
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 declare(strict_types=1);
 
 namespace Kleinweb\Lib\Tenancy\Exceptions;