Fails when ssh_config for host contains `ProxyJump none`

[cdleonard]

From ssh_config manual:

Setting the host to none disables this option entirely.

However pyinfra will attempt to proxy-jump through the literal hostname "none" and fail on the name resolution step.

The underlying paramiko SSHConfig library has custom handling for ProxyCommand none but not ProxyJump none. It might make sense for pyinfra to handle it itself because it already has a whole bunch of customization on top of paramiko.

There is a paramiko bug open for this: https://github.com/paramiko/paramiko/issues/2285