Update junit-plugin, junit-runtime, ... to 0.4.15

Author: scala-steward

project/plugins.sbt

@@ -4,4 +4,4 @@ addSbtPlugin("org.portable-scala" % "sbt-scalajs-crossproject" % "1.3.2")
 addSbtPlugin("org.scala-js" % "sbt-scalajs" % "1.13.2")
 
 addSbtPlugin("org.portable-scala" % "sbt-scala-native-crossproject" % "1.3.2")
-addSbtPlugin("org.scala-native" % "sbt-scala-native" % "0.4.14")
+addSbtPlugin("org.scala-native" % "sbt-scala-native" % "0.4.15")