ci: Slightly change the scheduled time

Originally, the build-verify.yml workflow was scheduled for 00:00 UTC,
but GitHub somehow was not scheduling. Change the frequency to a less
busy time.

Author: apyrgio

.github/workflows/build-verify.yml

@@ -2,7 +2,7 @@ name: Create reproducible builds for this repo
 
 on:
   schedule:
-    - cron: '0 0 * * *'
+    - cron: '0 4 * * *'
   workflow_dispatch:
   push: