Tooling to manually run a bulk changelog update from PR history rather than continuouly running a separate bot

[irismessage]

As a fork maintainer it would be useful to have a command line tool based on this repo which I could run once to update my working copy by adding an entry for every PR that isn't already included in the changelog, all at once. The webhook stuff is more effort for a small fork.

GitHub CLI is useful for this, I have a small script to add changelog entries with the correct date and time based on gh pr list --json but I didn't bother to reimplement parsing the PR description because it would be better if I could use this repo to do it
https://github.com/medabunny/imp-station-14/blob/master/Tools/changelog_from_prs.py