fix: action artifact version

Author: Tony-Rome

.github/workflows/pelican.yml

@@ -32,7 +32,7 @@ jobs:
         run: pelican content -s publishconf.py -o output
 
       - name: upload pages artifact
-        uses: actions/upload-pages-artifact@v2
+        uses: actions/upload-artifact@v4
         with:
           path: ./output