fixed preview.yml (#93)

Author: jitendravjh

.github/workflows/preview.yml

@@ -11,6 +11,8 @@ jobs:
     steps:
       - name: Checkout
         uses: actions/checkout@v4
+        with:
+          ref: ${{ github.event.pull_request.head.sha }}
 
       - name: Set up Quarto
         uses: quarto-dev/quarto-actions/setup@v2