Update billiard to 3.6.0.0

[pyup-bot]

This PR updates billiard from 3.5.0.3 to 3.6.0.0.

Changelog

3.6.0.0

--------------------

- Add support of sending parent process death signal.

- Previous fix for handling timeouts caused a problem in warm shutdowns due
to use of deepcopy.

We now use a shallow copy of the cache and do so only when it is needed.

- Cleanup old checks and workarounds for Python versions we no longer support.

3.5.0.5

--------------------

- Fix a crash when handling a timeout.
- Improve billiard.einfo.Frame compatibility with Python to avoid crashes when using Django.
- Cleanups.

3.5.0.4

--------------------

- Fix rebuild_ctype losing BufferedWrapper reference on Python 3.
- Deprecation warning with python 3.6 fixed.
- Correct spawn start method.

Links

• PyPI: https://pypi.org/project/billiard
• Changelog: https://pyup.io/changelogs/billiard/
• Repo: https://github.com/celery/billiard