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

Author: renovate[bot]

Diff for: .github/workflows/main.yml

@@ -85,7 +85,7 @@ jobs:
       - name: Build docs
         run: make docs
       - name: Deploy
-        uses: peaceiris/actions-gh-pages@v3
+        uses: peaceiris/actions-gh-pages@v4
         if: ${{ github.event_name == 'release' }}
         with:
           publish_branch: gh-pages