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/build.yml

@@ -25,7 +25,7 @@ jobs:
       - run: npm ci
       - run: npm run build
       - run: npm run opt
-      - uses: peaceiris/actions-gh-pages@v3.8.0
+      - uses: peaceiris/actions-gh-pages@v3.9.0
         with:
           github_token: ${{ secrets.GITHUB_TOKEN }}
           publish_dir: ./_site