Merge pull request #158 from scala-steward/update/sbt-scalajs-1.9.0

Update sbt-scalajs, scalajs-compiler, ... to 1.9.0

Author: mergify[bot]

project/plugins.sbt

@@ -1,5 +1,5 @@
 libraryDependencies += "org.scala-js" %% "scalajs-env-selenium" % "1.1.1"
-addSbtPlugin("org.scala-js" % "sbt-scalajs" % "1.8.0")
+addSbtPlugin("org.scala-js" % "sbt-scalajs" % "1.9.0")
 addSbtPlugin("org.scala-native" % "sbt-scala-native" % "0.4.3")
 addSbtPlugin("com.eed3si9n" % "sbt-projectmatrix" % "0.9.0")