chore(deps): update peaceiris/actions-gh-pages action to v4

Author: renovate[bot]

.github/workflows/book-cd.yml

@@ -21,7 +21,7 @@ jobs:
         uses: peaceiris/actions-mdbook@v1
       - run: mdbook build docs
       - name: Deploy
-        uses: peaceiris/actions-gh-pages@v3
+        uses: peaceiris/actions-gh-pages@v4
         with:
           github_token: ${{ secrets.GH_PAT }}
           publish_dir: ./docs/book