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

Author: typelevel-steward[bot]

project/plugins.sbt

@@ -1,5 +1,5 @@
 val sbtTlVersion = "0.8.2"
 addSbtPlugin("org.typelevel" % "sbt-typelevel" % sbtTlVersion)
 addSbtPlugin("org.typelevel" % "sbt-typelevel-mergify" % sbtTlVersion)
-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" % "0.5.8")