Description of the problem, including code/CLI snippet

This request is for supporting the ability to 'promote' a project label to a group one. This exists in the Gitlab API.

Specifically, https://docs.gitlab.com/ee/api/labels.html#promote-a-project-label-to-a-group-label

Expected Behavior

project.labels.promote(label_id)
or
gitlab project-label promote (CLI)

Actual Behavior

Promotion not supported

Specifications

• python-gitlab version: Latest
• API version you are using (v3/v4): v4
• Gitlab server version (or gitlab.com): Any