MQTTNet sends incorrect protocol version (83)

[victornor]

Describe the bug

Even though I'm specifying version V310, the client sends
10 df 04 00 06 4d 51 49 73 64 70 (83) 82 00 0f 00
instead of the expected
10 df 04 00 06 4d 51 49 73 64 70 (03) 82 00 0f 00

Which component is your bug related to?

Client (Both RC 5 and 4.3.7)

To Reproduce

Connect using websocket or mqtt with protocol V310, observe the connect packet.

Expected behavior

I expect a connect packet with the following data
10 df 04 00 06 4d 51 49 73 64 70 (03) 82 00 0f 00

Code example

// Websocket
var mqttOptions = new MqttClientOptionsBuilder()
        .WithWebSocketServer(x =>
            x.WithUri(uri).Build()
        )
        .WithProtocolVersion(MqttProtocolVersion.V310)
        .WithCleanSession()
        .Build();

await mqttClient.ConnectAsync(mqttOptions);

// MQTT
var mqttOptions = new MqttClientOptionsBuilder()
        .WithTcpServer(uri)
        .WithProtocolVersion(MqttProtocolVersion.V310)
        .WithCleanSession()
        .Build();

await mqttClient.ConnectAsync(mqttOptions);