Migrate build system to net8.0

[anpin]

Is your feature request related to a problem? Please describe.
Build pipeline for #359 fails and I'm not able to run fake locally as it depends on mono on linux. Build system and test targets should be updated to net8 similar to akkadotnet/akka.net#7008

Describe the solution you'd like
Build system uses latest net8 and fake6 tooling without mono dependency

Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.

Additional context
Add any other context or screenshots about the feature request here.