Update HttpServerBluePrint.scala

Author: pjfanning

http-core/src/main/scala/org/apache/pekko/http/impl/engine/server/HttpServerBluePrint.scala

@@ -48,6 +48,7 @@ import pekko.http.impl.util.LogByteStringTools._
 import scala.collection.immutable
 import scala.concurrent.{ ExecutionContext, Future, Promise }
 import scala.concurrent.duration.{ Deadline, Duration, DurationLong, FiniteDuration }
+import scala.jdk.DurationConverters._
 import scala.util.Failure
 import scala.util.control.{ NoStackTrace, NonFatal }