fix: use correct ref in preview workflow

Author: steveiliop56

.github/workflows/preview.yml

@@ -21,6 +21,7 @@ jobs:
         uses: actions/checkout@v4
         with:
           fetch-depth: 0
+          ref: ${{ github.head_ref}}
 
       - name: Setup bun
         uses: oven-sh/setup-bun@v2