Downgrading Sphinx to 4.0.3 as docs fail with latest (4.1.0)

Author: jaidisido

requirements-dev.txt

@@ -14,7 +14,7 @@ pytest-xdist==2.3.0
 pytest-timeout==1.4.2
 pydot==1.4.2
 twine==3.4.1
-sphinx==4.1.0
+sphinx==4.0.3
 sphinx_bootstrap_theme==0.7.1
 nbsphinx==0.8.6
 nbsphinx-link==1.3.0