Bump up scalacheck version to 1.13.4.
Bump up scalacheck version to 1.13.4.

cheeseng/scalatest,cheeseng/scalatest,dotty-staging/scalatest,dotty-staging/scalatest,scalatest/scalatest,scalatest/scalatest,cheeseng/scalatest,scalatest/scalatest,dotty-staging/scalatest