cd: fix action versioning

Author: rowenslee

.github/workflows/jekyll.yml

@@ -49,7 +49,7 @@ jobs:
           JEKYLL_ENV: production
       - name: Upload artifact
         # Automatically uploads an artifact from the './_site' directory by default
-        uses: actions/upload-pages-artifact@v3
+        uses: actions/upload-pages-artifact@v4
 
   # Deployment job
   deploy: