ci: periodic-update triggers on push only when files.list updates

Signed-off-by: Camber Huang <[email protected]>

Author: CamberLoid

.github/workflows/periodic-update.yml

@@ -3,6 +3,7 @@ name: Periodic updates
 on:
   push:
     branches: [ master ]
+    paths: [ ./files.list ]
   schedule:
     - cron: "0 0 * * *"
   workflow_dispatch: ~