Consider adding a PR analytics workflow

### Describe the feature you'd like supported

Periodically generate a report of who is reviewing PRs, how long PRs take to get reviewed, etc.

### Proposed solution

See https://github.com/marketplace/actions/pull-request-analytics

Perhaps generate a report monthly?

### Additional context

If for some reason we don't like the action in the marketplace, one could write a separate script:
https://stackoverflow.com/questions/42267930/i-need-to-gather-review-statistics-from-github-on-our-project