Bump peaceiris/actions-gh-pages from 3.9.3 to 4.0.0 (#176)

Bumps [peaceiris/actions-gh-pages](https://github.com/peaceiris/actions-gh-pages) from 3.9.3 to 4.0.0.
- [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@v3.9.3...v4.0.0)

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

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

Diff for: .github/workflows/deploy_book.yml

@@ -42,7 +42,7 @@ jobs:
 
       - name: Deploy book on push
         if: ${{ success() && github.event_name == 'push' }}
-        uses: peaceiris/actions-gh-pages@v3.9.3
+        uses: peaceiris/actions-gh-pages@v4.0.0
         with:
           github_token: ${{ secrets.GITHUB_TOKEN }}
           publish_dir: ./brainhack_book/_build/html