Removed `last_seen_at` from the api queries
Removed `last_seen_at` from the api queries

refs https://github.com/TryGhost/Team/issues/1393

- This prevents the `last_seen_at` from being sent to the API
- In the future the API will accept this property, this is a temporary fix

TryGhost/Ghost,TryGhost/Ghost,TryGhost/Ghost