Workflow update - Upgrade upload-pages-artifact to v3 (#820)

Author: sbenmoussati

.github/workflows/docs.yml

@@ -36,7 +36,7 @@ jobs:
         env:
           JEKYLL_ENV: production
       - name: Upload artifact
-        uses: actions/upload-pages-artifact@v1
+        uses: actions/upload-pages-artifact@v3
         with:
           path: "docs/_site/"