Synthesize instead of dynamic for url

Author: jcavar

MQTTClient/MQTTClient/MQTTWebsocketTransport/MQTTWebsocketTransport.m

@@ -17,9 +17,9 @@ @interface MQTTWebsocketTransport()
 @implementation MQTTWebsocketTransport
 @synthesize state;
 @synthesize delegate;
+@synthesize url;
 @dynamic host;
 @dynamic port;
-@dynamic url;
 
 - (instancetype)init {
     self = [super init];