fix import

Author: Jaap van der Plas

src/main/scala/io/iohk/ethereum/testmode/TestmodeConsensus.scala

@@ -15,6 +15,7 @@ import io.iohk.ethereum.ledger.{BlockExecutionError, BlockExecutionSuccess, Bloc
 import io.iohk.ethereum.nodebuilder._
 import io.iohk.ethereum.utils.BlockchainConfig
 import monix.eval.Task
+import io.iohk.ethereum.consensus.pow.validators.ValidatorsExecutor
 
 class TestmodeConsensus(
     override val vm: VMImpl,