update Artifact from v2 to v4

Author: Kimberley Cook

.github/workflows/main.yml

@@ -36,7 +36,7 @@ jobs:
           npm ci
           npm run build
       - name: Upload artifact
-        uses: actions/upload-pages-artifact@v2
+        uses: actions/upload-pages-artifact@v3
         with:
           path: 'dist'
       - name: Deploy to GitHub Pages