Update docs.yml (#59)

Update custom Actions workflow to:
actions/upload-pages-artifact@v3
actions/deploy-pages@v4

Author: AGonzalezNicolas

.github/workflows/docs.yml

@@ -47,10 +47,10 @@ jobs:
           make src-browser
 
       - name: Upload documentation artifacts
-        uses: actions/upload-pages-artifact@v2
+        uses: actions/upload-pages-artifact@v3
         with:
           path: "docs/_build/html"
 
       - name: Deploy to GitHub Pages
         id: deployment
-        uses: actions/deploy-pages@v2
+        uses: actions/deploy-pages@v4