made workflow changes

Author: rahul-infra

.github/workflows/terraform-checks.yaml

@@ -14,6 +14,9 @@ jobs:
     steps:
       - name: Checkout
         uses: actions/checkout@v5
+        with:
+          ref: ${{github.event.pull_request.head.ref }}
+          fetch-depth: 0
 
       - name: Temporarily merge PR branch
         if: ${{ github.event_name == 'pull_request' }}