zephyr/test: Fix copyright header
Remove . after Authors.
BRANCH=None
TEST=None
Code-Coverage: Zoss
Tested-by: Jeremy Bettis
-/* Copyright 2022 The ChromiumOS Authors.
+/* Copyright 2022 The ChromiumOS Authors
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
