[ETCM-355] Remove unused method

Author: lukasz-golebiewski

src/main/scala/io/iohk/ethereum/network/p2p/Message.scala

@@ -1,7 +1,5 @@
 package io.iohk.ethereum.network.p2p
 
-import akka.util.ByteString
-
 import cats.implicits._
 
 import io.iohk.ethereum.utils.Logger
@@ -12,12 +10,7 @@ trait Message {
 }
 
 trait MessageSerializable extends Message {
-
-  //DummyImplicit parameter only used to differentiate from the other toBytes method
-  def toBytes(implicit di: DummyImplicit): ByteString
-
   def toBytes: Array[Byte]
-
   def underlyingMsg: Message
 }