Bump myst-parser from 4.0.1 to 5.0.0 in /requirements (#16027)

Bumps [myst-parser](https://github.com/executablebooks/MyST-Parser) from 4.0.1 to 5.0.0.
- [Release notes](https://github.com/executablebooks/MyST-Parser/releases)
- [Changelog](https://github.com/executablebooks/MyST-Parser/blob/master/CHANGELOG.md)
- [Commits](executablebooks/MyST-Parser@v4.0.1...v5.0.0)

---
updated-dependencies:
- dependency-name: myst-parser
  dependency-version: 5.0.0
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

requirements/docs.txt

@@ -1,4 +1,4 @@
 # For buildings docs locally
 sphinx==8.2.3
 readthedocs-sphinx-ext==2.2.5
-myst-parser==4.0.1
+myst-parser==5.0.0