[skip ci] fix thread locking workflow to actually be daily

.github/workflows/lock.yml

@@ -3,7 +3,7 @@ name: Lock threads
 on:
   # Daily
   schedule:
-    - cron: '0 * * * *'
+    - cron: '0 0 * * *'
   # Manual trigger
   workflow_dispatch:
     inputs: