Order stored messages

Drop new messages from the MqttNet library queue
to ensure sending stored messages according to
how they were streamed by the user

Signed-off-by: nedimtokic <nedim.tokic@secomind.com>

AstarteDeviceSDKCSharp/Transport/MQTT/AstarteMqttTransport.cs

@@ -171,7 +171,7 @@ public override async Task Connect()
                 .WithAutoReconnectDelay(TimeSpan.FromSeconds(5))
                 .WithMaxPendingMessages(10000)
                 .WithPendingMessagesOverflowStrategy(
-                    MQTTnet.Server.MqttPendingMessagesOverflowStrategy.DropOldestQueuedMessage)
+                    MQTTnet.Server.MqttPendingMessagesOverflowStrategy.DropNewMessage)
                 .Build();
 
             if (!_client.IsStarted)