fix GetValidatorKey()

Author: yungwine

mytoncore/mytoncore.py

@@ -1911,12 +1911,13 @@ def MoveCoinsFromHW(self, wallet, destList, **kwargs):
 
 	def GetValidatorKey(self):
 		vconfig = self.GetValidatorConfig()
-		for validator in vconfig["validators"]:
+		validators = sorted(vconfig["validators"], key=lambda i: i['election_date'], reverse=True)
+		for validator in validators:
 			validatorId = validator["id"]
 			key_bytes = base64.b64decode(validatorId)
 			validatorKey = key_bytes.hex().upper()
 			timestamp = get_timestamp()
-			if timestamp > validator["election_date"]:
+			if validator["election_date"] < timestamp < validator["expire_at"]:
 				return validatorKey
 		raise Exception("GetValidatorKey error: validator key not found. Are you sure you are a validator?")
 	#end define