Bump sphinx-design from 0.2.0 to 0.3.0 (#739)

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/docs.txt

@@ -6,7 +6,7 @@ sphinx-rtd-theme>=1.0.0, <2.0.0
 myst-parser>=0.14, <0.19
 sphinxcontrib-apidoc>=0.3.0, <0.4.0
 nbsphinx>=0.8.5, <0.9.0
-sphinx_design==0.2.0  # Pinning for now as sphinx_design is v.new and still in flux. 
+sphinx_design==0.3.0  # Pinning for now as sphinx_design is v.new and still in flux. 
 ipykernel>=5.1.0, <7.0.0 # required for executing notebooks via nbsphinx
 ipython>=7.2.0, <9.0.0 # required for executing notebooks nbsphinx
 # dependencies required for imports to work and docs to render properly (as mocking doesn't work well)