Update CODEOWNERS (see bitfireAT/davx5-ose#1949)

Author: rfc2822

.github/CODEOWNERS

@@ -1,4 +1,8 @@
 # See https://docs.github.com/de/repositories/managing-your-repositorys-settings-and-features/customizing-your-repository/about-code-owners
+# For combination with "Require review from code owners" for main branch.
 
-# For combination with "Require review from code owners" for main branch:
-*      @bitfireAT/app-dev
+# Dependabot
+gradle/**   @bitfireAT/app-dev
+
+# everything else
+*   @rfc2822