backup Spoon Github data (issue and pull request)

Recently, Github has blocked or deleted entire projects for political reasons.

Just in case, we should backup all our Github data which is important development and process knowledge.

We would cron this and push a tarball somewhere.

No files, tests, backup scope, or destination are named in the issue. Start by defining which GitHub issue and pull-request data must be preserved, where the tarball should be pushed, and how the cron job will run; done means a repeatable scheduled backup is produced and stored reliably.

Written by the indexing model from the issue text.