chore: Use conventional commits for Dependabot bumps

Signed-off-by: Christoph Wurst <christoph@winzerhof-wurst.at>

.github/dependabot.yml

@@ -7,3 +7,6 @@ updates:
     time: "03:00"
     timezone: Europe/Paris
   open-pull-requests-limit: 10
+  commit-message:
+    prefix: "chore"
+    include: "scope"