gh workflows: add license headers

Signed-off-by: Alex Tereschenko <alext.mkrs@gmail.com>

.github/workflows/build_and_test.yaml

@@ -1,3 +1,11 @@
+# Copyright (c) 2025 Tom Ingleby, Alex Tereschenko
+#
+# This program and the accompanying materials are made available under the terms
+# of the MIT license which is available at
+# https://projects.eclipse.org/license/mit-license-mit.
+#
+# SPDX-License-Identifier: MIT
+
 name: Build and test
 
 on: