Add copyright notes

test/test.hpp

@@ -1,3 +1,11 @@
+/**
+ * Copyright (c) 2025 Michal Sledz
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/.
+ */
+
 #include <functional>
 #include <iostream>