How to perform gitlab-ce with Mattermost upgrade from gitlab 14.7 and Mattermost 6.2 to latest

I’ve been reading upgraded nodts from
https://docs.mattermost.com/upgrade/important-upgrade-notes.html
But I’m unsure what steps I need to take for my particular install.
Please provide any guidance you might offer for my self-hosted situation.
My goal is to upgrade this install since I and all users are receiving warnings
about compability with server.

Thanks

$ docker images
gitlab/gitlab-ce             14.7.3-ce.0   6f6c9f0dd251   11 months ago   2.39GB

From docker shell:

root@gitlab:/# apt-cache search gitlab-ce
gitlab-ce - GitLab Community Edition (including NGINX, Postgres, Redis)

docker containerized install
GitLab 14.7.3 (with Mattermost)
GitLab Shell 13.22.2
GitLab Workhorse v14.7.3
GitLab API v4
GitLab Pages 1.51.0
Ruby 2.7.5p203
Rails 6.1.4.4
PostgreSQL 12.7
Redis 6.0.16
Mattermost Team Edition - Mattermost Version: 6.2.2
Database Schema Version: 6.2.2
Database: postgres