chore(deps): bump peaceiris/actions-gh-pages from v3 to v3.8.0

Bumps [peaceiris/actions-gh-pages](https://github.com/peaceiris/actions-gh-pages) from v3 to v3.8.0.
- [Release notes](https://github.com/peaceiris/actions-gh-pages/releases)
- [Changelog](https://github.com/peaceiris/actions-gh-pages/blob/main/CHANGELOG.md)
- [Commits](https://github.com/peaceiris/actions-gh-pages/compare/v3...068dc23d9710f1ba62e86896f84735d869951305)

Signed-off-by: dependabot[bot] <support@github.com>

.github/workflows/docs.yml

@@ -15,7 +15,7 @@ jobs:
         run: make docs
 
       - name: Deploy
-        uses: peaceiris/actions-gh-pages@v3
+        uses: peaceiris/actions-gh-pages@v3.8.0
         with:
           github_token: ${{ secrets.GITHUB_TOKEN }}
           publish_dir: ./site