deps: bump actions/deploy-pages from 3 to 4

Pull-Request: #5022.

Author: dependabot[bot]

.github/workflows/docs.yml

@@ -42,5 +42,5 @@ jobs:
     steps:
       - name: Deploy to GitHub Pages
         id: deployment
-        uses: actions/deploy-pages@v3
+        uses: actions/deploy-pages@v4