Add copyright header

Signed-off-by: Gabriel Adrian Samfira <gsamfira@cloudbasesolutions.com>

cache/github_client.go

@@ -1,3 +1,16 @@
+// Copyright 2025 Cloudbase Solutions SRL
+//
+//	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.
 package cache
 
 import (