TLS 1.2 is not supported

[molovsson]

When setting up a secure websocket listener, only SSL 3.0 and TLS 1.0 are supported, due to passing SslProtocols.Default to AuthenticateAsServer and AuthenticateAsServerAsync. This causes an issue on machines that only allow TLS 1.2.

If targeting .NET 4.7 and later, the AuthenticateAsServer versions that don't take the SslProtocols parameter (but takes the other parameters currently used) can be used to let the OS choose the best protocol to use. In earlier versions, SslProtocols.Tls | SslProtocols.Tls11 | SslProtocols.Tls12 can be used to only support the current TLS protocols.

[deniszykov]

SSL configuration is supported in my fork:
https://github.com/deniszykov/WebSocketListener
WebSocketListenerOptions.SupportedSslProtocols