Workflow: cleanup-pr-preview delete correct folder (#63)

Author: StanFromIreland

.github/workflows/cleanup-pr-preview.yml

@@ -13,6 +13,6 @@ jobs:
           ref: gh-pages
       - run: git config user.name "github-actions[bot]"
       - run: git config user.email "41898282+github-actions[bot]@users.noreply.github.com"
-      - run: git rm ${{ github.ref_name }}
-      - run: git commit -m 'Cleaning up gh-pages after ${{ github.ref_name }}'
+      - run: git rm -rf ${{ github.event.number }}
+      - run: git commit -m 'Cleaning up gh-pages after ${{ github.event.number }}'
       - uses: ad-m/github-push-action@master