Update sbt-scalajs, scalajs-compiler, ... to 1.15.0

Author: http4s-steward[bot]

project/plugins.sbt

@@ -10,5 +10,5 @@ libraryDependencies += "org.http4s" %% "http4s-ember-server" % http4sVersion
 addSbtPlugin("org.http4s" % "sbt-http4s-org" % "0.16.2")
 addSbtPlugin("com.armanbilge" % "sbt-bundlemon" % "0.1.4")
 addSbtPlugin("org.scalameta" % "sbt-mdoc" % "2.5.2")
-addSbtPlugin("org.scala-js" % "sbt-scalajs" % "1.14.0")
+addSbtPlugin("org.scala-js" % "sbt-scalajs" % "1.15.0")
 addSbtPlugin("com.eed3si9n" % "sbt-buildinfo" % "0.11.0")