Update more-itertools to 8.1.0

[pyup-bot]

This PR updates more-itertools from 7.2.0 to 8.1.0.

Changelog

8.1.0

See the [release notes](https://github.com/erikrose/more-itertools/blob/ba499fc5f38c7441271c3f147cfd9abbc587556d/docs/versions.rst).

8.0.2

See [the release notes](https://github.com/erikrose/more-itertools/blob/b2c747c2bf642bb9e193a3428bb0052614d420b4/docs/versions.rst802).

8.0.1

See the [release notes](https://github.com/erikrose/more-itertools/blob/765c71b265bb6b34f28fc14500f0f4ab2d3d36ef/docs/versions.rst801) for details.

8.0.0

See [the release notes](https://github.com/erikrose/more-itertools/blob/4661c942c49fe891a80b50c201983d00db75af13/docs/versions.rst800) for details.

Links

• PyPI: https://pypi.org/project/more-itertools
• Changelog: https://pyup.io/changelogs/more-itertools/
• Repo: https://github.com/erikrose/more-itertools
• Docs: https://pythonhosted.org/more-itertools/

[pyup-bot]

Closing this in favor of #212