Update myst-parser[linkify] requirement from <4,>=2 to >=2,<5

Updates the requirements on [myst-parser[linkify]](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...v4.0.0)

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

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

docs/requirements.txt

@@ -1,4 +1,4 @@
 furo==2024.5.6
-myst-parser[linkify]>=2,<4
+myst-parser[linkify]>=2,<5
 sphinx>=7,<8.2
 sphinx-copybutton>=0.3.1,<1