Notice: trailofbits/gh-action-pip-audit is now pypa/gh-action-pip-audit

Thanks for using `gh-action-pip-audit` in your CI!

I'm filing this issue (as an actual human being) to let you know that we recently became a PyPA member project, and correspondingly changed our repo from [`trailofbits/gh-action-pip-audit`](https://github.com/trailofbits/gh-action-pip-audit) to [`pypa/gh-action-pip-audit`](https://github.com/pypa/gh-action-pip-audit).

As part of keeping your workflows up-to-date, we recommend that you change your workflow slugs to `pypa/gh-action-pip-audit`. Once you do that, Dependabot (or whatever other tooling you use) should track updates to the action correctly.

P.S.: I'm filing these issues instead of making PRs, so that you (as maintainers) can confirm the trustworthiness of the change. If you'd prefer me to make a PR instead, give me a ping and I'll do so.