Upgrade upload-pages-artifact action to v2

Author: ziagham

.github/workflows/pages-deploy.yml

@@ -55,7 +55,7 @@ jobs:
           bundle exec htmlproofer _site --disable-external --check-html --allow_hash_href
 
       - name: Upload site artifact
-        uses: actions/upload-pages-artifact@v1
+        uses: actions/upload-pages-artifact@v2
         with:
           path: "_site${{ steps.pages.outputs.base_path }}"