https://github.com/drone/go-scm/blob/4a12b862aa80a510c8097d899bd00571e7b296e0/scm/driver/gitlab/webhook.go#L31 https://docs.gitlab.com/ee/user/project/integrations/webhooks.html#merge-request-events https://docs.gitlab.com/ee/system_hooks/system_hooks.html#merge-request-events
