Add missing import

Author: marcos-iov

src/test/java/co/rsk/federate/signing/utils/TestUtils.java

@@ -17,6 +17,7 @@
 import co.rsk.crypto.Keccak256;
 import co.rsk.peg.Federation;
 import co.rsk.peg.FederationMember;
+import co.rsk.peg.StandardMultisigFederation;
 import java.lang.reflect.Field;
 import java.math.BigInteger;
 import java.security.SecureRandom;