Merge branch 'update-mattermost-tag-6.7.0-bb.0' into 'master'

Update Mattermost to 6.7.0

Closes platform-one/big-bang/apps/collaboration-tools/mattermost#48

See merge request platform-one/big-bang/bigbang!1681

chart/values.yaml

@@ -1167,7 +1167,7 @@ addons:
     git:
       repo: https://repo1.dso.mil/platform-one/big-bang/apps/collaboration-tools/mattermost.git
       path: "./chart"
-      tag: "6.6.0-bb.0"
+      tag: "6.7.0-bb.0"
 
     # -- Flux reconciliation overrides specifically for the Mattermost Package
     flux: {}