Implement API versioning in varfish-cli

**Is your feature request related to a problem? Please describe.**
The package `varfish-cli` does not use API versioning. This makes errors hard to track.

**Describe the solution you'd like**
Implement API versioning as exposed by the VarFish server.

**Describe alternatives you've considered**
N/A

**Additional context**
- https://github.com/bihealth/varfish-server/issues/333