Github tokens do not work entirely as expected

[nickmarden]

Expected: by providing a Github token, I can pull and replicate a Github repo

Actual: There is an implied expectation that the user running github2gitlab will have both GH auth access (i.e. be logged in to Github) and also provide a Github token for Github API calls.

I'm a user who does NOT have Github user auth for a repo I am trying to replicate. I have only a token. Unfortunately code like this assumes that git CLI shell commands can be executed due to existing GH login auth in the existing shell environment.

I will provide a fix for this issue. It requires replacing --github-token (a token) with --github-auth (a username + token)