ETCM-165: Update benchmark using Hex.

Author: aakoshh

src/benchmark/scala/io/iohk/ethereum/rlp/RLPSpeedSuite.scala

@@ -7,7 +7,6 @@ import io.iohk.ethereum.domain._
 import io.iohk.ethereum.network.p2p.messages.CommonMessages.SignedTransactions._
 import io.iohk.ethereum.utils.Logger
 import org.scalacheck.Gen
-import org.bouncycastle.util.encoders.Hex
 import org.scalatest.funsuite.AnyFunSuite
 import org.scalatestplus.scalacheck.{ScalaCheckDrivenPropertyChecks, ScalaCheckPropertyChecks}