Update pytest-leaks to 0.3.1

[pyup-bot]

This PR updates pytest-leaks from 0.2.2 to 0.3.1.

Changelog

0.3.1

- Add `pytest.mark.no_leak_check` for skipping leak checks (29, 31).
- Fix issues with pytest output capture (25).
- Fix pytest-xdist compatibility (33).

0.3.0

- Compatibility with Pytest 4 and 5.
- Compatibility with Python 3.6 and above.
- Bugfixes (4, 5, 6, 7, 8, 10, 11, 14, 15).

Links

• PyPI: https://pypi.org/project/pytest-leaks
• Changelog: https://pyup.io/changelogs/pytest-leaks/
• Repo: https://github.com/abalkin/pytest-leaks