Update Mattermost to 5.16.5 (GitLab 12.5)
Mattermost 5.16.5 contains a fix for a high severity security issue as mentioned in the changelog here. Mattermost 5.17.3 and 5.18.1 contain the same fix, and MRs will be submitted for those shortly.
Related to https://gitlab.com/gitlab-org/omnibus-gitlab/issues/4977
Edited by 🤖 GitLab Bot 🤖