PSubset.subType is unsound

[Odomontois]

https://scastie.scala-lang.org/Odomontois/V9g3cTrsTui4xpc3qhp0wA

import tofu.optics._
val s = Subset[List[String], List[Nothing]]
val x : List[Int] = s.getOption(List("sound", "of", "silence")).toList.flatten
x.sum

produces "Class cast exception`

Monocle macro has the same problem

https://scastie.scala-lang.org/Odomontois/V9g3cTrsTui4xpc3qhp0wA/2

We need to come with some more wise method to write that macro.