Bump myst-parser from 0.18.1 to 4.0.0

Bumps [myst-parser](https://github.com/executablebooks/MyST-Parser) from 0.18.1 to 4.0.0.
- [Release notes](https://github.com/executablebooks/MyST-Parser/releases)
- [Changelog](https://github.com/executablebooks/MyST-Parser/blob/master/CHANGELOG.md)
- [Commits](executablebooks/MyST-Parser@v0.18.1...v4.0.0)

---
updated-dependencies:
- dependency-name: myst-parser
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]