Feature Request: Import Gitlab group milestones

My gitlab projects make use of group milestones which are currently ignored by the existing migrator.

I’ve been able to successfully get them in by tweaking gitlab.go GetMilestones to add in the IncludeParentMilestones option as follows;

ms, _, err := g.client.Milestones.ListMilestones(g.repoID, &gitlab.ListMilestonesOptions{
State: &state,
IncludeParentMilestones: gitlab.Bool(true),
ListOptions: gitlab.ListOptions{
Page: i,
PerPage: perPage,
}, nil, gitlab.WithContext(g.ctx))

However it would probably be better to add an option to the import api?