Update sbt-scalajs-crossproject to 1.3.1 (#226)

Co-authored-by: Yang, Bo <[email protected]>

Author: scala-steward

project/plugins.sbt

@@ -1,6 +1,6 @@
 addSbtPlugin("org.scala-js" % "sbt-scalajs" % "1.13.2")
 
-addSbtPlugin("org.portable-scala" % "sbt-scalajs-crossproject" % "1.2.0")
+addSbtPlugin("org.portable-scala" % "sbt-scalajs-crossproject" % "1.3.1")
 
 addSbtPlugin("ch.epfl.scala" % "sbt-scalajs-bundler" % "0.21.1")