Bump sphinx-design from 0.2.0 to 0.3.0 in /requirements (#431)

Bumps [sphinx-design](https://github.com/executablebooks/sphinx-design) from 0.2.0 to 0.3.0.
- [Release notes](https://github.com/executablebooks/sphinx-design/releases)
- [Changelog](https://github.com/executablebooks/sphinx-design/blob/main/CHANGELOG.md)
- [Commits](executablebooks/sphinx-design@v0.2.0...v0.3.0)

---
updated-dependencies:
- dependency-name: sphinx-design
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

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

Author: dependabot[bot]

requirements/requirements_docs.txt

@@ -5,7 +5,7 @@ nbsphinx==0.8.9
 pytest-sphinx==0.4.0
 sphinx-autobuild==2021.3.14
 sphinxcontrib-napoleon==0.7
-sphinx_design==0.2.0
+sphinx_design==0.3.0
 sphinx-notfound-page==0.8.3
 sphinx-copybutton==0.5.0
 sphinx-gallery==0.11.0