bump up book theme for accessibility

Author: zingale

requirements.txt

@@ -15,6 +15,6 @@ codespell
 # docs
 jupyter-book<2
 sphinx_design
-sphinx-book-theme>=1.0.1
+git+https://github.com/executablebooks/sphinx-book-theme.git
 pydata-sphinx-theme>=0.13.3
 jupyterlab_myst