Added license headers.

.github/workflows/Release.yml

@@ -1,3 +1,25 @@
+# ==============================================================================
+# Authors:            Patrick Lehmann
+#                     Unai Martinez-Corral
+#
+# License:
+# ==============================================================================
+# Copyright 2020-2021 pyTooling
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+# SPDX-License-Identifier: Apache-2.0
+# ==============================================================================
 name: Release
 
 on: