Use outside of Github

Hi,

Has anyone had any luck using this outside of Github, for example in Gitlab CI?

We use Gitlab CI at work. I'd love to be able to import some helper functions from this package and use that to generate the comparison Markdown. I can handle all the plumbing it up to Gitlab itself (leaving comments on merge requests etc) but I don't want to re-do all the logic for the comparison itself.

(this assumes App Directory support would be added, as we're all-in on `app`!)