TASTy reader should error early on unsupported Scala 3 version #13152
Description
based on https://contributors.scala-lang.org/t/sbt-1-12-1-and-unmoored-scala-reflect-scala-compiler-issue/7376/8 it seems that Scala 3.7 will remain the final Scala 3 version to be supported by the Scala 2 TASTy reader
on the Scala 2 side, I think we should:
- error early and comprehensibly if someone tries to use the TASTy reader with an unsupported Scala 3 version
- highlight the issue in the Scala 2.13.19 release notes
- document the TASTy Reader somewhere (there isn't currently a doc page for it), including all relevant version compatibility information