Bump actions/deploy-pages from 3 to 4 (#294)

Author: dependabot[bot]

.github/workflows/publish-docs.yml

@@ -47,4 +47,4 @@ jobs:
           path: './site'
       - name: Deploy to GitHub Pages
         id: deployment
-        uses: actions/deploy-pages@v3
+        uses: actions/deploy-pages@v4