Use PR HEAD as action version

Author: rossjrw

.github/workflows/preview-example.yml

@@ -14,9 +14,8 @@ jobs:
     if: github.event.pull_request.head.repo.full_name == github.repository
     steps:
       - name: Checkout
-        uses: actions/checkout@v3
-
+        uses: actions/checkout@v4
       - name: Deploy preview
-        uses: rossjrw/pr-preview-action@v1
+        uses: rossjrw/pr-preview-action@${{ github.event.pull_request.head.sha }}
         with:
           source-dir: test