`make update-schema` - undocumented dependencies

`make update-schema` is supposed to run the `go generate` command, which is useful for generating the database mapper files.

However, the required `lxd-generate` and `mockery` (which are needed in the `microceph/database` files) and their versions are not documented. Additionally, using the latest versions generates diffs (the following imports are missing: `context`, `net/http`, `strings`, `github.com/canonical/microcluster/v2/cluster`), plus using `mockvery` v3 results in errors (does not support the ``--name`` argument, but `mockery` v2 does).