Add support for Scala 2.13.7

[vincenzobaz]

closes #537

[SethTisue]

Since it's that easy, I've added it to the Scala 2 release steps: scala/scala-dev@cb1e492

[vincenzobaz]

Great idea @SethTisue. We could also go down the rabbit hole and investigate potential automation of the task

[OlegYch]

Since it's that easy, I've added it to the Scala 2 release steps: scala/scala-dev@cb1e492

it actually requires updating kind-projector as well 0603528

[SethTisue]

it actually requires updating kind-projector as well

ah, good point. I'm adding this to the release steps:

• Open a ticket in the kind-projector repo, suggesting they publish
• Scastie: open PR adding new version (modeled on Add support for Scala 2.13.7 #538)
  • note that the PR won't be mergeable until kind-projector has published; and if kind-projector's version number has changed, ScalaTarget.scala will need updating