ci(stale-workflow): adjust cron schedule frequency

- Update workflow to run less frequently: 3 days each -> 14 days each

Signed-off-by: Dragon1573 <49941141+Dragon1573@users.noreply.github.com>

Author: Dragon1573

.github/workflows/stale.yml

@@ -3,8 +3,8 @@ name: Stale Issue Management
 
 on:
   schedule:
-    # Run at 16:00 UTC every 3 days (corresponds to 00:00 Beijing time)
-    - cron: '0 16 */3 * *'
+    # Run at 16:00 UTC every 14 days (corresponds to 00:00 CST)
+    - cron: '0 16 */14 * *'
   # Allow manual triggering
   workflow_dispatch: