Action to update AUTHORS

[mmarchini]

As title says, we could use an Action to keep AUTHORS in sync with git history. Could either be on push or a scheduled Action (daily or weekly) if we don't want it to run too frequently.

Originally posted by @mmarchini in #34694 (comment)

[richardlau]

Most of the manual updates usually catch one or two duplicates that need to be added to the mailmap, so we'd probably still need periodic manual updates as I imagine those will be hard to spot via automation.

[mmarchini]

The Action could create a PR, it would help us identify any duplicates and with a regular cadence the list of added names should be small (making it easier to review as well).

[targos]

We now have an action that runs weekly.