Bump myst-parser from 5.0.0 to 5.1.0 in /docs

Bumps [myst-parser](https://github.com/executablebooks/MyST-Parser) from 5.0.0 to 5.1.0.
- [Release notes](https://github.com/executablebooks/MyST-Parser/releases)
- [Changelog](https://github.com/executablebooks/MyST-Parser/blob/master/CHANGELOG.md)
- [Commits](executablebooks/MyST-Parser@v5.0.0...v5.1.0)

---
updated-dependencies:
- dependency-name: myst-parser
  dependency-version: 5.1.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

docs/requirements.txt

@@ -1,3 +1,3 @@
 furo==2025.12.19
 sphinx==9.1.0
-myst_parser==5.0.0
+myst_parser==5.1.0