Update actions/upload-pages-artifact action to v2

Author: renovate[bot]

.github/workflows/deploy-site.yml

@@ -47,7 +47,7 @@ jobs:
       - name: docusaurus build
         run: ./gradlew docusaurusBuild
 
-      - uses: actions/upload-pages-artifact@v1
+      - uses: actions/upload-pages-artifact@v2
         with:
           path: ./site/build