chore(deps): bump peaceiris/actions-gh-pages from 3 to 4 (#508)

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Author: dependabot[bot]

.github/workflows/docs.yml

@@ -34,7 +34,7 @@ jobs:
       - name: Generate documentation
         run: poetry run sphinx-build -b html ./ ./_build
       - name: Deploy to GitHub Pages
-        uses: peaceiris/actions-gh-pages@v3
+        uses: peaceiris/actions-gh-pages@v4
         if: ${{ github.event_name == 'push' && github.ref == 'refs/heads/main' }}
         with:
           publish_branch: docs