chore(deps): update actions/download-artifact action to v6

Author: renovate[bot]

.github/workflows/ci.yml

@@ -119,7 +119,7 @@ jobs:
           cache: 'pnpm'
 
       # use artifacts to share the playground across different jobs
-      - uses: actions/download-artifact@v5
+      - uses: actions/download-artifact@v6
         with:
           name: build-output