Fix code smell by removing no needed call to toString method

Author: nathanieliov

src/main/java/co/rsk/federate/BtcToRskClient.java

@@ -16,6 +16,7 @@
 import co.rsk.panic.PanicProcessor;
 import co.rsk.peg.BridgeUtils;
 import co.rsk.peg.Federation;
+import co.rsk.peg.FederationMember;
 import co.rsk.peg.PegUtilsLegacy;
 import co.rsk.peg.PeginInformation;
 import co.rsk.peg.btcLockSender.BtcLockSender.TxSenderAddressType;