Discussions not backed up

[ClaudioFriederich]

Discussions are not backed up. There is also no command line argument to include them, and they are not included in --all.

[ClaudioFriederich]

It turns out that the REST API from GitHub does not have discussion support, and GitHub does not plan to add it. Their GraphQL API does, but using that would be an unfeasible change in an existing REST-based app like this.