Use hashCode of the Agg[PathRef] instead of the hashCode of the Paths

scalajslib/src/mill/scalajslib/worker/ScalaJSWorker.scala

@@ -15,7 +15,7 @@ private[scalajslib] class ScalaJSWorker extends AutoCloseable {
   private def bridge(toolsClasspath: Agg[mill.PathRef])(implicit ctx: Ctx.Home) = {
     // toolsClasspath is stable and made of external libraries which have the versions
     // in the file names. So we use the paths string to hash since it's ~50x faster
-    val classloaderSig = toolsClasspath.iterator.map(p => p.path.hashCode).sum
+    val classloaderSig = toolsClasspath.hashCode
     scalaJSWorkerInstanceCache match {
       case Some((sig, bridge)) if sig == classloaderSig => bridge
       case _ =>