The v2.8 refers to the internal database format, not the frontend version v1.3.
It just means, the VIC-20 MDB file was made using an older version of the GameBase frontend (v1.2).
just click YES to update it, and it will work with v1.3 final.
A newer version of GB20 is slowly being done, but delayed indefinitely due to lack of time on my part (life, work, daughter!) that supports the newer GB front end properly. Maybe one day…