fix: add license header to lint-changed.sh

Author: iennae

.github/scripts/lint-changed.sh

@@ -1,6 +1,18 @@
 #!/usr/bin/env bash
+# Copyright 2026 Google LLC
+#
+# 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.
 
-# Exit immediately if a command fails, or if an unset variable is used
 set -euo pipefail
 
 EVENT_NAME="${1:-local}"