Move config for prs

[paribaker]

tn gh-all-prs relies on a config file to be present in the directory where the CLI is, so if you have it in root it looks for .config IMO this should be a config inside of a directory e.g .tncli/.config to avoid any clashes with any other files in the root.

[whusterj]

Ah, my bad! .config should definitely be global. I meant for it to live in ~/.tn/config. That's how the AWS CLI does it.

Separately, I'm thinking we need to come up with some way to write reliable tests that can catch issues like this.

[whusterj]

I'll handle this as part of #14