Added license notices at the beginnings of the files. Updates license to the Apache License 2.0.

tests/json/test_serializer.py

@@ -1,3 +1,17 @@
+#  Copyright 2026 jCloud Services GbR
+#
+#  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
+#
+#      https://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.
+
 from src.config_parser.serialize.json import serialize as serialize_json
 
 def test_serialize_json():