Update sphinx from 4.3.1 to 9.0.3

Author: pyup-bot

docs/requirements.txt

@@ -3,7 +3,7 @@ myst-parser==0.16.1
 nbsphinx==0.8.7
 nbsphinx-link==1.3.0
 numpydoc==1.1.0
-sphinx==4.3.1
+sphinx==9.0.3
 sphinxcontrib-bibtex==2.4.1
 sphinxawesome-theme==3.2.1
 sphinx-gallery==0.11.1