Having merged the drop-headtracker PR we now have a DB schema change in `unstable` compared to `release-v7.0.0`:
- https://github.com/sigp/lighthouse/pull/6744
There is a DB downgrade available, however this needs to be applied manually and it's usually a bit of a hassle.
This PR bumps the version on `unstable` to `v7.1.0-beta.0` _without_ actually cutting a `v7.1.0-beta.0` release, so that we can tell at a glance which schema version a node is using.
47a85cd118