After a combined PR is merged, we have leftover PRs that clutter the UI and immediately conflict with others.

In our previous home-grown version of this action, we appended each PR in the merged list with Closes # to activate GitHub's functionality to close those out on merge.

Something like:

prs.push('Closes #' + pull.node.number + ' ' + pull.node.title);

Is this something that you'd entertain adding to this action?