Remain compatible with SBT versions < 1.5 (#117)
Remain compatible with SBT versions < 1.5 (#117)

Replace ScalaArtifacts.isScala3 with CrossVersion.partialVersion, so that projects using SBT versions prior to 1.5 can still use sbt-web-scalajs.

ScalaArtifacts.isScala3 is only available in SBT 1.5.x, whereas CrossVersion.partialVersion exists in all 1.x versions.
vmunier/sbt-web-scalajs,vmunier/sbt-web-scalajs