Update furo to 2021.11.23

[pyup-bot]

This PR updates furo from 2021.10.9 to 2021.11.23.

Changelog

2021.11.23

- Improve code block styling.
- Explicitly declare compatibility constraints for pygments.
- Break words in API documentation, when the words are too long.
- Drop the `def ` on function and method signatures.
- Reduce the font-weight in `sig-prename`.

2021.11.16

- Fix a typo, that broke the sidebar highlight logic.

2021.11.15

- Tweak API documentation presentation to match pdoc3's style.
- Bring back browser-specific prefixes, for compatibility.

2021.11.12.1

- Fix RECORD file contents.

2021.11.12

- Adopt `sphinx-theme-builder`, which runs the JS-based asset build process during the regular Python build process.
- Rework the build pipeline to be webpack-based.
- Tweak colours in dark mode.
- Present better error messages on misconfiguration.
- Tweak presentation of blockquotes, to be more visually distinct.
- Stylize topics like admonitions, as specified in the reStructuredText spec.
- Handle long single words in the sidebar.
- Only hide Sphinx from the footer, when `show_sphinx` is set to `False`.

Links

• PyPI: https://pypi.org/project/furo
• Changelog: https://pyup.io/changelogs/furo/