Insert License in Testing files

Author: aashishpatil-g

Tests/Unit/HeaderTests.swift

@@ -1,9 +1,16 @@
+// Copyright 2024 Google LLC
 //
-//  HeaderTests.swift
-//  FirebaseDataConnect
+// 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
 //
-//  Created by Aashish Patil on 9/18/24.
+//      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.
 
 import FirebaseCore
 @testable import FirebaseDataConnect