test-client-sync: Fix UDP connection test.

Rather than passing in a vanilla object, we should pass in something
that implements the settimeout method.

test/test_client_sync.py

@@ -97,7 +97,10 @@ def testUdpClientAddressFamily(self):
     def testUdpClientConnect(self):
         ''' Test the Udp client connection method'''
         with patch.object(socket, 'socket') as mock_method:
-            mock_method.return_value = object()
+            class DummySocket(object):
+                def settimeout(self, *a, **kwa):
+                    pass
+            mock_method.return_value = DummySocket()
             client = ModbusUdpClient()
             self.assertTrue(client.connect())