glean/.github/pull_request_template.md

Pull Request checklist

• Quality: This PR builds and tests run cleanly
  • make test runs without emitting any warnings
  • make lint runs without emitting any errors
• Tests: This PR includes thorough tests or an explanation of why it does not
• Changelog: This PR includes a changelog entry or an explanation of why it does not need one
  • Any breaking changes to language binding APIs are noted explicitly