Update doc preview cleanup CI job (#248)

.github/workflows/CleanupDocPreview.yml → .github/workflows/DocPreviewCleanup.yml

@@ -1,29 +1,31 @@
-name: Cleanup Doc Preview
+name: Doc Preview Cleanup
 
 on:
   pull_request:
     types: [closed]
 
 jobs:
-  cleanup-doc-preview:
+  doc-preview-cleanup:
     runs-on: ubuntu-latest
+    permissions:
+      contents: write
     steps:
       - name: Checkout gh-pages branch
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           ref: gh-pages
-      - name: Delete preview
+      - name: Delete preview and history + push changes
         run: |
             if [ -d "previews/PR$PRNUM" ]; then
               git config user.name "Documenter.jl"
               git config user.email "documenter@juliadocs.github.io"
               git rm -rf "previews/PR$PRNUM"
-              git commit -m "delete preview for $PRNUM"
-              git push origin gh-pages:gh-pages
+              git commit -m "delete preview"
+              git branch gh-pages-new $(echo "delete history" | git commit-tree HEAD^{tree})
+              git push --force origin gh-pages-new:gh-pages
             fi
         env:
             PRNUM: ${{ github.event.number }}
 
-# adapted from here:
+# copied from here:
 # https://juliadocs.github.io/Documenter.jl/stable/man/hosting/#gh-pages-Branch
-# without history cleanup