docs: add import

Author: Roiocam

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

@@ -26,6 +26,7 @@ import scala.concurrent.Future
 object LoggingDocSpec {
 
   //#deadletters
+  import akka.actor.DeadLetter
   import akka.actor.typed.Behavior
   import akka.actor.typed.eventstream.EventStream.Subscribe
   import akka.actor.typed.scaladsl.Behaviors