chore(deps): Bump peaceiris/actions-gh-pages from 3 to 4 (#288)

Bumps [peaceiris/actions-gh-pages](https://github.com/peaceiris/actions-gh-pages) from 3 to 4.
- [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...v4)

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

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

Author: dependabot[bot]

.github/workflows/mkdocs.yml

@@ -79,7 +79,7 @@ jobs:
           echo -e "User-agent: *\nSitemap: https://${{ env.CUSTOM_DOMAIN }}/sitemap.xml" > "./site/robots.txt"
 
       - name: Deploy docs
-        uses: peaceiris/actions-gh-pages@v3
+        uses: peaceiris/actions-gh-pages@v4
         if: github.ref == 'refs/heads/master'
         with:
           personal_token: ${{ secrets.DEPLOYMENT_PERSONAL_ACCESS_TOKEN }}