add deploy preview

Author: acolytec3

.github/workflows/test-deploy.yaml

@@ -26,4 +26,9 @@ jobs:
       - name: Test build website
         run: |
           npm run build
-          npm run build:docs
+          npm run build:docs
+      - name: Deploy preview
+        if: github.event.action != 'closed' 
+        uses: rossjrw/pr-preview-action@v1
+        with:
+          source-dir: ./build/docs/gatsby/public