Update Mattermost Operator to 1.13.0

New Ironbank image is available: registry1.dso.mil/ironbank/opensource/mattermost/mattermost-operator:v1.13.0

Upstream updates are here: https://github.com/mattermost/mattermost-operator/tree/v1.13.0

Release notes: https://github.com/mattermost/mattermost-operator/releases/tag/v1.13.0