🚀 Feature: Allow --title to be an array

### Bug Report Checklist

- [X] I have pulled the latest `main` branch of the repository.
- [X] I have [searched for related issues](https://github.com/JoshuaKGoldberg/prune-github-notifications/issues?q=is%3Aissue) and found none that matched my issue.

### Overview

Right now, the `--title` option can only be a single `string`, and the Node.js `title` option property can only be a single `RegExp`.

But, I'm imagining folks will want to provide multiple options for that. It'd be inconvenient to have to list a bunch of not-similar options as cases in a single regexp.

Let's change `--title` / `title` to allow an array of inputs!

### Additional Info

_No response_