Onwards and upwards

[armanbilge]

Bumps Scala 3 to 3.1.x and Scalacheck to 1.16.x. Closes #878. Supersedes #868.

[adampauls]

I'm dying of curiosity: what is stopping this PR from being merged? Lots of upstream stuff seems to be blocked on it?

[armanbilge]

@adampauls see the extensive discussion in typelevel/cats#4016. So, historically it's been a controversial issue, although it may not be as much anymore.

FWIW my mind has been stuck on this PR too :) any @typelevel/scalacheck maintainer feel inclined to merge, or at least add another approval?

[SethTisue]

I've asked on #878 for some input from the Center and/or Virtus

[julienrf]

Please note that Scala 3.1.2 will support -scala-output-version. Would you consider using this feature to emit Scala 3.0-compatible TASTy files?

[armanbilge]

What is the story with -scala-output-version and Scala Native, which doesn't support Scala 3.0? Do we have to special case our builds?

-scala-output-version is extremely important, and for sure we should use it to emit 3.1-compatible TASTy from 3.2+ which is just around the corner. But pinning to 3.0 just doesn't seem worth it IMHO