Update sbt-scalajs, scalajs-compiler, ... to 1.13.0 (#379)

Author: scala-steward

project/plugins.sbt

@@ -1,6 +1,6 @@
 addSbtPlugin("com.github.sbt" % "sbt-ci-release" % "1.5.11")
 addSbtPlugin("com.typesafe" % "sbt-mima-plugin" % "1.1.2")
-addSbtPlugin("org.scala-js" % "sbt-scalajs" % "1.12.0")
+addSbtPlugin("org.scala-js" % "sbt-scalajs" % "1.13.0")
 addSbtPlugin("org.portable-scala" % "sbt-scalajs-crossproject" % "1.2.0")
 addSbtPlugin("org.scala-js" % "sbt-jsdependencies" % "1.0.2")
 addSbtPlugin("io.get-coursier" % "sbt-shading" % "2.1.1")