Update the TLS version used in TransparentClientHandler.cs

Author: keyoti

src/Titanium.Web.Proxy/TransparentClientHandler.cs

@@ -71,7 +71,7 @@ private async Task handleClient(TransparentBaseProxyEndPoint endPoint, TcpClient
                                                     await CertificateManager.CreateServerCertificate(certName);
 
                             // Successfully managed to authenticate the client using the certificate
-                            await sslStream.AuthenticateAsServerAsync(certificate, false, SslProtocols.Tls, false);
+                            await sslStream.AuthenticateAsServerAsync(certificate, false, SslProtocols.Tls12, false);
 
                             // HTTPS server created - we can now decrypt the client's traffic
                             clientStream = new HttpClientStream(clientStream.Connection, sslStream, BufferPool, cancellationToken);