Revert "Fix outdated action version" (#529)

This reverts commit 46d99f3.

Author: chrmarti

.github/workflows/publish.yml

@@ -58,7 +58,7 @@ jobs:
           destination: ./_site
 
       - name: Upload artifact
-        uses: actions/upload-pages-artifact@v4
+        uses: actions/upload-pages-artifact@v3
 
   # Deployment job
   deploy: