Bump myst-parser from 3.0.1 to 4.0.0 in /docs

Bumps [myst-parser](https://github.com/executablebooks/MyST-Parser) from 3.0.1 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@v3.0.1...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]

docs/requirements.txt

@@ -1,5 +1,5 @@
 Sphinx==7.2.6
-myst-parser==3.0.1
+myst-parser==4.0.0
 sphinx-copybutton==0.5.2
 sphinx-design==0.5.0
 sphinx_external_toc==1.0.1