Bump default SSL protocol version

[MrAdam]

The default SSL protocol version in SslSettings is set to SslProtocols.Tls which is insecure and deprecated. Looking at the documentation for SslProtocols, SslProtocols.Tls is obsolete starting in .NET 7.

It seems to me like SslProtocols.None which Allows the operating system to choose the best protocol to use, and to block protocols that are not secure. Unless your app has a specific reason not to, you should use this field. is the best option here.

Looking at the SSL documentation for the .NET RabbitMq.Client under TLS Support, it is also noted that:

RabbitMQ .NET client 5.x series uses TLSv1.0 by default.

Starting with RabbitMQ .NET client 6.0 the default changes to SslProtocols.None, which means the default is picked by the .NET framework or the operating system depending on app context switches.

If a connection that uses SslProtocols.None to pick a suitable TLS version fails, the client will retry with TLSv1.2 enabled explicitly. This reduces the need for explicit configuration on the application developer's end in environments where automatic TLS version selection is disabled, not available or otherwise cannot be relied on.

Modern .NET frameworks versions default to TLSv1.2.

And I can see that this package is using RabbitMq.Client version 6.5.0, which again points to SslProtocols.None as the best option.

This would also solve the issue #80 of connections to RabbitMQ in AWS not working by default, unless explicitly specifying SslProtocols.Tls12, as AWS defaults to TLSv1.2.

[MrAdam]

I'd be happy to make the PR, if you (@mookid8000) thinks it's alright to change this default?

[mookid8000]

@MrAdam great! 👍

[mookid8000]

Fixed by #108 - it's out as Rebus.RabbitMq 9.0.0-alpha02 on NuGet.org now