dendrite/.github/PULL_REQUEST_TEMPLATE.md

### Pull Request Checklist

<!-- Please read https://matrix-org.github.io/dendrite/development/contributing before submitting your pull request -->

* [ ] I have added Go unit tests or [Complement integration tests](https://github.com/matrix-org/complement) for this PR _or_ I have justified why this PR doesn't need tests
* [ ] Pull request includes a [sign off below using a legally identifiable name](https://matrix-org.github.io/dendrite/development/contributing#sign-off) _or_ I have already signed off privately

Signed-off-by: `Your Name <your@email.example.org>`