Merge pull request #3190 from nextcloud/ci/renovate-pub-versioning

Author: provokateurin

.github/renovate.json

@@ -16,6 +16,10 @@
     "automerge": true
   },
   "packageRules": [
+    {
+      "matchDatasources": ["dart"],
+      "versioning": "npm"
+    },
     {
       "matchManagers": ["pub"],
       "matchDatasources": ["dart-version", "flutter-version"],