Merge pull request #479 from typelevel/update/sbt-scalajs-1.20.1

Update sbt-scalajs, scalajs-compiler, ... to 1.20.1

Author: sh0hei

project/plugins.sbt

@@ -1,5 +1,5 @@
 addSbtPlugin("pl.project13.scala" % "sbt-jmh"                       % "0.4.8")
-addSbtPlugin("org.scala-js"       % "sbt-scalajs"                   % "1.18.2")
+addSbtPlugin("org.scala-js"       % "sbt-scalajs"                   % "1.20.1")
 addSbtPlugin("org.scala-native"   % "sbt-scala-native"              % "0.4.17")
 addSbtPlugin("org.portable-scala" % "sbt-scala-native-crossproject" % "1.3.2")
 val sbtTypelevelVersion = "0.8.2"