Fix py312-docutils0.18 tests.

Author: domdfcoding

tox.ini

@@ -350,7 +350,7 @@ commands =
     python --version
     python -m pytest --cov=html_section -r aR tests/ {posargs}
 
-[testenv:py313-docutils0.18]
+[testenv:py{312,313}-docutils0.18]
 setenv =
     PYTHONDEVMODE=1
     PIP_DISABLE_PIP_VERSION_CHECK=1