doc: update header in tests
diff --git a/test/run_all_tests.py b/test/run_all_tests.py
index 8c02dbf..39114af 100644
--- a/test/run_all_tests.py
+++ b/test/run_all_tests.py
@@ -1,5 +1,9 @@
#! /usr/bin/env python
-
+#
+# This file is part of pySerial - Cross platform serial port support for Python
+# (C) 2001-2015 Chris Liechti <cliechti@gmx.net>
+#
+# SPDX-License-Identifier: BSD-3-Clause
"""\
UnitTest runner. This one searches for all files named test_*.py and collects
all test cases from these files. Finally it runs all tests and prints a