Bump peaceiris/actions-gh-pages from 3.8.0 to 3.9.0

Bumps [peaceiris/actions-gh-pages](https://github.com/peaceiris/actions-gh-pages) from 3.8.0 to 3.9.0.
- [Release notes](https://github.com/peaceiris/actions-gh-pages/releases)
- [Changelog](https://github.com/peaceiris/actions-gh-pages/blob/main/CHANGELOG.md)
- [Commits](peaceiris/actions-gh-pages@v3.8.0...v3.9.0)

---
updated-dependencies:
- dependency-name: peaceiris/actions-gh-pages
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

.github/workflows/deploy-book.yml

@@ -37,7 +37,7 @@ jobs:
           rm -f book.zip
 
       - name: Deploy to GitHub Pages
-        uses: peaceiris/actions-gh-pages@v3.8.0
+        uses: peaceiris/actions-gh-pages@v3.9.0
         if: github.ref == 'refs/heads/main'
         with:
           github_token: ${{ secrets.GITHUB_TOKEN }}

.github/workflows/deploy-preview.yaml

@@ -115,7 +115,7 @@ jobs:
           github.event.workflow_run.conclusion == 'success'
           && steps.find-pull-request.outputs.number != ''
           && steps.fc.outputs.comment-id != ''
-        uses: peaceiris/actions-gh-pages@v3.8.0
+        uses: peaceiris/actions-gh-pages@v3.9.0
         with:
           github_token: ${{ secrets.GITHUB_TOKEN }}
           publish_dir: notebooks/_build/html