Update sbt-scalajs, scalajs-compiler, ... to 1.9.0 (#872)

Author: scala-steward

project/plugins.sbt

@@ -9,7 +9,7 @@ addSbtPlugin("com.typesafe"                      % "sbt-mima-plugin"
 addSbtPlugin("de.heikoseeberger"                 % "sbt-header"                    % "5.6.5")
 addSbtPlugin("org.portable-scala"                % "sbt-scala-native-crossproject" % "1.1.0")
 addSbtPlugin("org.portable-scala"                % "sbt-scalajs-crossproject"      % "1.1.0")
-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("org.scalameta"                     % "sbt-mdoc"                      % "2.3.0")
 addSbtPlugin("org.scalameta"                     % "sbt-scalafmt"                  % "2.4.6")