bench: Use toJSON

Author: locallycompact

hydra-cluster/bench/Bench/EndToEnd.hs

@@ -329,7 +329,7 @@ newTx registry client tx = do
           , invalidAt = Nothing
           , confirmedAt = Nothing
           }
-  send client $ input "NewTx" ["transaction" .= serialiseToTextEnvelope Nothing tx]
+  send client $ input "NewTx" ["transaction" .= toJSON tx]
 
 data WaitResult
   = TxInvalid {transactionId :: TxId, reason :: Text}