Fix PR preview deployment

Author: reakaleek

.github/workflows/preview-build.yml

@@ -51,7 +51,7 @@ jobs:
         if: github.event_name != 'pull_request' || steps.check-files.outputs.any_changed == 'true'
         uses: actions/checkout@v4
         with: 
-          persist-credentials: false # test
+          persist-credentials: false
 
       - name: Generate path prefix
         env:
@@ -78,7 +78,7 @@ jobs:
         id: metadata
         env:
           PR_NUMBER: ${{ github.event.pull_request.number }}
-          REF: ${{ github.sha }}
+          REF: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.sha ||github.sha }}
           SHOULD_DEPLOY: ${{ github.event_name == 'pull_request' && steps.check-files.outputs.any_changed || 'true' }}
         run: |
           cat << EOF > deployment_metadata.json