docs: update to latest sphinx-design (#486)

* docs: fix use of sphinx-design

* Update pyproject.toml

Author: agoose77

pyproject.toml

@@ -82,7 +82,7 @@ rtd = [
     "plotly",
     "sphinx-book-theme~=0.3.0",
     "sphinx-copybutton",
-    "sphinx-design~=0.1.0",
+    "sphinx-design~=0.4.0",
     "sphinxcontrib-bibtex",
     "sympy",
 ]