ci(renovate): Shorten the commit message for Gradle dependencies

Change the commit message topic to `{{depName}}` instead of the default
`dependency {{depName}}` [1]. "dependency" is redundant as the
conventional commit type is already "deps".

[1]: https://docs.renovatebot.com/configuration-options/#commitmessagetopic

Signed-off-by: Martin Nonnenmacher <[email protected]>

renovate.json

@@ -18,6 +18,10 @@
   ],
   "labels": ["dependencies"],
   "packageRules": [
+    {
+      "matchManagers": ["gradle"],
+      "commitMessageTopic": "{{depName}}"
+    },
     {
       "matchPackageNames": [
         "com.atlassian.jira:jira-rest-java-client-api",