Update sbt-scalajs-crossproject to 1.2.0 (scala#174)

Author: scala-steward

project/plugins.sbt

@@ -1,3 +1,3 @@
 addSbtPlugin("org.scala-lang.modules" % "sbt-scala-module" % "3.0.1")
-addSbtPlugin("org.portable-scala" % "sbt-scalajs-crossproject" % "1.1.0")
+addSbtPlugin("org.portable-scala" % "sbt-scalajs-crossproject" % "1.2.0")
 addSbtPlugin("org.scala-js" % "sbt-scalajs" % "1.9.0")