Scheduled weekly dependency update for week 18

[pyup-bot]

Update websockets from 8.0.2 to 8.1.

Changelog

8.1

...

* Added compatibility with Python 3.8.

Links

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

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[pyup-bot]

Closing this in favor of #35