Is your feature request related to a problem? Please describe.

Ruby 3.0 will release very soon, the new feature Fiber Scheduler may significant improve Ruby server app.

My friend working on the first Fiber Scheduler implementation called EVT https://github.com/dsh0416/evt

The benchmark shows impressive.

Although there's still lacking DB drivers, Redis, etc. to adapt the fiber scheduler so Rack-based app can't get such performance, but I think it is time now.

Describe the solution you'd like

Let Puma support Ruby 3.0 Fiber Scheduler