Update jekyll.yml back to v3?

Author: dcnb

.github/workflows/jekyll.yml

@@ -43,7 +43,7 @@ jobs:
           JEKYLL_ENV: production
       - name: Upload artifact
         # Automatically uploads an artifact from the './_site' directory by default
-        uses: actions/upload-pages-artifact@v4
+        uses: actions/upload-pages-artifact@v3
   # Deployment job
   deploy:
     environment: