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](peaceiris/actions-gh-pages@v3...068dc23)

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

.github/workflows/release.yml

@@ -56,7 +56,7 @@ jobs:
       run: mkdocs build
 
     - name: Deploy
-      uses: peaceiris/actions-gh-pages@v3
+      uses: peaceiris/actions-gh-pages@v3.8.0
       env:
         ACTIONS_DEPLOY_KEY: ${{ secrets.ACTIONS_DEPLOY_KEY }}
         PUBLISH_BRANCH: gh-pages