Start CI 15min earlier (#427)

#426 was created 42 minutes after the scheduled time, missing the daily update window for rupicola, and delaying coq/coq#19310 (comment) by 24 hours. In lieu of getting a cron that can actually keep time, I'll fudge this one just a bit for now.

.github/dependabot.yml

@@ -14,6 +14,6 @@ updates:
     directory: "/"
     schedule:
       interval: "daily"
-      time: "06:00"
+      time: "05:45"
     labels:
       - "submodules"