As noted in #50, there are some cases where we have a mix of
`currentVersion` `fixedVersion` and a `lockedVersion`, but are only
pulling the `lockedVersion`.

As per discussion on the Renovate Slack[0], we should amend this logic
to pull the right fields where appropriate. Before we do, we can rename
the underlying fields in the database and domain model.

This is a breaking change, due to the database schema, and change in
domain models.

[0]: https://renovatebot.slack.com/archives/CAFH752JU/p1680881967858539