mattermost update to 11.6.2-bb.0

Package Merge Request

Package Changes

https://repo1.dso.mil/big-bang/product/packages/mattermost/-/blob/11.6.2-bb.0/CHANGELOG.md

Package MR

big-bang/product/packages/mattermost!364 (merged)

For Issue

Closes big-bang/product/packages/mattermost#269 (closed)

Upgrade Notices

n/a