Update myst-parser requirement from ~=2.0 to ~=3.0

Updates the requirements on [myst-parser](https://github.com/executablebooks/MyST-Parser) to permit the latest version.
- [Release notes](https://github.com/executablebooks/MyST-Parser/releases)
- [Changelog](https://github.com/executablebooks/MyST-Parser/blob/master/CHANGELOG.md)
- [Commits](executablebooks/MyST-Parser@v2.0.0...v3.0.0)

---
updated-dependencies:
- dependency-name: myst-parser
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

docs/requirements-doc.txt

@@ -1,5 +1,5 @@
 -e .
-myst-parser~=2.0
+myst-parser~=3.0
 sphinx~=7.3.7
 furo==2024.1.29
 types-docutils~=0.21