fix compile

Author: Roiocam

akka-actor-typed-tests/src/test/scala/akka/actor/typed/eventstream/LoggingDocSpec.scala

@@ -80,7 +80,7 @@ class LoggingDocSpec extends ScalaTestWithActorTestKit with AnyWordSpecLike with
 
   "allow registration to dead letters from start up" in {
     // #deadletters
-    val system = ActorSystem(Behaviors.setup[Void] { context =>
+    ActorSystem(Behaviors.setup[Void] { context =>
       context.spawn(DeadLetterListener(), "DeadLetterListener", Props.empty)
       Behaviors.empty
     }, "System")