Update sphinx-design requirement in /requirements

Updates the requirements on [sphinx-design](https://github.com/executablebooks/sphinx-design) to permit the latest version.
- [Release notes](https://github.com/executablebooks/sphinx-design/releases)
- [Changelog](https://github.com/executablebooks/sphinx-design/blob/main/CHANGELOG.md)
- [Commits](executablebooks/sphinx-design@v0.3.0...v0.6.0)

---
updated-dependencies:
- dependency-name: sphinx-design
  dependency-type: direct:production
...

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

requirements/documentation.txt

@@ -6,6 +6,6 @@ myst-parser[linkify]>=0.13,<3.1
 sphinx>=3.1,<8
 sphinx-autobuild==2024.4.16
 sphinx-copybutton>=0.2,<1
-sphinx-design>=0.3,<0.6
+sphinx-design>=0.6.0,<0.7
 sphinx-sitemap>=2.4,<3
 toml>=0.10.2