Merge pull request #9702 from tk0miya/test_with_docutils-latest

test: Do test with the HEAD of docutils

tox.ini

@@ -31,6 +31,13 @@ setenv =
 commands=
     python -X dev -m pytest --durations 25 {posargs}
 
+[testenv:du-latest]
+commands =
+    git clone https://repo.or.cz/docutils.git {temp_dir}/docutils
+    python -m pip install {temp_dir}/docutils/docutils
+    rm -rf {temp_dir}/docutils
+    {[testenv]commands}
+
 [testenv:flake8]
 basepython = python3
 description =