enable license header checks

Author: rnro

.github/workflows/pull_request.yml

@@ -8,9 +8,6 @@ jobs:
   soundness:
     name: Soundness
     uses: swiftlang/github-workflows/.github/workflows/soundness.yml@main
-    with:
-      license_header_check_project_name: "SwiftPrometheus"
-      license_header_check_enabled: false
 
   unit-tests:
     name: Unit tests

.license_header_template

@@ -0,0 +1,13 @@
+@@===----------------------------------------------------------------------===@@
+@@
+@@ This source file is part of the SwiftPrometheus open source project
+@@
+@@ Copyright (c) YEARS the SwiftPrometheus project authors
+@@ Licensed under Apache License v2.0
+@@
+@@ See LICENSE.txt for license information
+@@ See CONTRIBUTORS.txt for the list of SwiftPrometheus project authors
+@@
+@@ SPDX-License-Identifier: Apache-2.0
+@@
+@@===----------------------------------------------------------------------===@@