Add Mattermost 3.10.0 upgrade to CHANGELOG.md
Mattermost upgraded to 3.10.0 in 9.3.
@marin please see comment in !1645 (merged). It seems that Mattermost is still on v3.9 in 9.3 RC5.
Edited by GitLab Release Tools Bot
Mattermost upgraded to 3.10.0 in 9.3.
@marin please see comment in !1645 (merged). It seems that Mattermost is still on v3.9 in 9.3 RC5.