Automatic sync to ROOT repo

[HDembinski]

I think we can make a CI job that runs once a day and checks whether there was a new release of the ROOT repo, and then update this repo automatically. It could probably even automatically add an issue to update iminuit with a reminder to update the externals.

@henryiii What do you think?

[henryiii]

I'd probably suggest making it once a week - most importantly, it should be manually trigerable so you can immediately update after a release that we want to use for some reason. :) It should be able to make the PR (as long as it's GHA) to update.

[henryiii]

Oh, I see you meant an iMinuit issue, nice, cross-repo is a little tricker, but might be doable.