Update to new LTS version 9.5
"Support for Mattermost Server v8.1 Extended Support Release is coming to the end of its life cycle on May 15, 2024. Upgrading to Mattermost Server v9.5 or later is recommended." https://docs.mattermost.com/upgrade/release-lifecycle.html
This updates the lts container to the latest Extended Support Release version.
Pending dsop/dccscr#2915 (closed)