Revert "[fix] docutils v0.17 incompatibility to previeous v0.16"

This reverts commit 4557d58919.

see https://github.com/sphinx-doc/sphinx/issues/9088

requirements-dev.txt

@@ -8,7 +8,6 @@ transifex-client==0.14.2
 selenium==3.141.0
 twine==3.4.1
 Pallets-Sphinx-Themes==2.0.0
-docutils==0.16
 Sphinx==4.0.1
 sphinx-issues==1.2.0
 sphinx-jinja==1.1.1