Adding tests in CI

[TonioGela]

It will be helpful to have tests in CI that check that the toolkit is able to compile a few test scripts.

I'm not sure we can achieve something like this, but we can try. WDYT @armanbilge?

[TonioGela]

Probably having a few lines like

//> using dep toolkit typelevel::@current_snapshot@

import cats.effect.*

object Hello extends IOApp.Simple {
  def run = IO.println("Hello")
}

and a CI job that compiles it

- uses: VirtusLab/scala-cli-setup@main
- run: scala-cli compile hello-ce.scala

will do