chore: remove dependabot commit-message config (#20)

Let it auto-detect conventional commits format.

Co-Authored-By: Claude Opus 4.5 <[email protected]>

Change-Id: Icbaab1dc1abe56b0398e44a4645dedb002f7072d
Claude-Session-Id: 43e5bb59-bfd1-4f17-982a-657235752c0d

Author: jd

.github/dependabot.yml

@@ -4,6 +4,4 @@ updates:
     directory: /
     schedule:
       interval: weekly
-    commit-message:
-      prefix: "deps:"
     open-pull-requests-limit: 5