Add support for the following fields in the [Groups API](https://docs.gitlab.com/api/groups/): - only_allow_merge_if_all_discussions_are_resolved - only_allow_merge_if_pipeline_succeeds - allow_merge_on_skipped_pipeline ## Implementation Guide - Read the `CONTRIBUTING.md` guide for setting up your local development environment and clone the community fork of this project. - Add the three fields to any `Group` structs used in `groups.go`. So structs returned when getting groups and structs used to update groups. - Add tests, ideally also integration tests. - Run `make reviewable` before raising an MR.