Update myst-parser to 4.0.0

[pyup-bot]

This PR updates myst-parser from 3.0.1 to 4.0.0.

Changelog

4.0.0

This release bumps the supported versions of:

- Python to ``3.10`` and greater
- Sphinx to ``>=7,<9``
- Docutils to ``>=0.19,<0.22``

Additionally, footnotes are now parsed similar to the corresponding reStructuredText, in that resolution (between definitions and references) and ordering is now deferred to transforms on the doctree (in <gh-pr:931>).

This allows for the proper interaction with other docutils/sphinx transforms, including those that perform translations,
and logging of warnings for duplicate/unreferenced footnote definitions and also for footnote references with no definitions.

See the [footnotes guide](syntax/footnotes) for more information.

**Full Changelog**: [v3.0.1...v4.0.0](https://github.com/executablebooks/MyST-Parser/compare/v3.0.1...v4.0.0)

Links

• PyPI: https://pypi.org/project/myst-parser
• Changelog: https://data.safetycli.com/changelogs/myst-parser/