* drop public submodule replace directive
During development of the public/ submodule, a replace directive remained that was both unnecessary and harmful as discussed in https://community.mattermost.com/private-core/pl/w77sh7igwpfb9ecj5o4jjjbbyo.
Remove that, and bump the explicit dependency (even though we use go.work) to v0.0.6 so the import paths match (e.g. `mattermost` vs `mattermost-server`).
* make modules-tidy
* consistently setup-go-work
* fix build-api-spec
* fix mmctl test template
* fix workflow copy/paste typo