Update sbt-scala-native to 0.3.9

Author: scala-steward

project/plugins.sbt

@@ -7,7 +7,7 @@ addSbtPlugin("org.scala-js"       % "sbt-scalajs"                   % "0.6.26")
 addSbtPlugin("org.portable-scala" % "sbt-crossproject"              % "0.6.0")
 addSbtPlugin("org.portable-scala" % "sbt-scalajs-crossproject"      % "0.6.0")
 addSbtPlugin("org.portable-scala" % "sbt-scala-native-crossproject" % "0.6.0")
-addSbtPlugin("org.scala-native"   % "sbt-scala-native"              % "0.3.8")
+addSbtPlugin("org.scala-native"   % "sbt-scala-native"              % "0.3.9")
 addSbtPlugin("com.47deg"          % "sbt-microsites"                % "0.7.18")
 
 scalacOptions += "-deprecation"