chore(gha): bump actions/deploy-pages from 3 to 4 (#39)

Requires to bump actions/upload-pages-artifact from 2 to 3.

.github/workflows/deploy-demo.yml

@@ -39,7 +39,7 @@ jobs:
 
       - name: Upload artifact
         # Automatically uploads an artifact from the './_site' directory by default
-        uses: actions/upload-pages-artifact@v2
+        uses: actions/upload-pages-artifact@v3
         with:
           # Path of the directory containing the static assets.
           path: ./dist
@@ -68,4 +68,4 @@ jobs:
     steps:
       - name: Deploy to GitHub Pages
         id: deployment
-        uses: actions/deploy-pages@v3
+        uses: actions/deploy-pages@v4