feat(nextcloud_test): mark presets function as test group

Signed-off-by: Nikolas Rimikis <leptopoda@users.noreply.github.com>

Author: Leptopoda

packages/nextcloud_test/lib/src/presets.dart

@@ -1,3 +1,4 @@
+import 'package:meta/meta.dart';
 import 'package:nextcloud_test/nextcloud_test.dart';
 import 'package:nextcloud_test/src/models/models.dart';
 import 'package:test/test.dart';
@@ -6,6 +7,7 @@ import 'package:test/test.dart';
 typedef NextcloudTesterCallback = void Function(NextcloudTester tester);
 
 /// All tests for apps that depend on the server version must be wrapped with this method and pass along the preset.
+@isTestGroup
 void presets(
   String presetGroup,
   String app,