ci: fix branch name from main to master in workflow

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

Author: CamberLoid

.github/workflows/periodic-update.yml

@@ -2,7 +2,7 @@ name: Periodic updates
 
 on:
   push:
-    branches: [ main ]
+    branches: [ master ]
   schedule:
     - cron: "0 0 * * *"
   workflow_dispatch: ~