Also fix license header check checkout

Author: josvazg

.github/workflows/license-header-check.yml

@@ -9,12 +9,17 @@ jobs:
     steps:
       - name: Checkout code
         uses: actions/checkout@v5
+        with:
+          ref: ${{github.event.pull_request.head.sha}}
+
       - name: Set up Go
         uses: actions/setup-go@v6
         with:
           go-version-file: "${{ github.workspace }}/go.mod"
+
       - name: Install addlicense
         run: go install github.com/google/addlicense@latest
+
       - name: Check license headers
         run: |
           $(go env GOPATH)/bin/addlicense \