Merge Docutils master tests into the main workflow

.github/workflows/docutils-latest.yml

@@ -1,29 +0,0 @@
-name: Test with the HEAD of docutils
-
-on:
-  schedule:
-  - cron: "0 0 * * SUN"
-  workflow_dispatch:
-
-permissions:
-  contents: read
-
-jobs:
-  test:
-    if: github.repository_owner == 'sphinx-doc'
-    runs-on: ubuntu-latest
-
-    steps:
-    - uses: actions/checkout@v3
-    - name: Set up Python
-      uses: actions/setup-python@v4
-      with:
-        python-version: 3
-    - name: Check Python version
-      run: python --version
-    - name: Install graphviz
-      run: sudo apt-get install graphviz
-    - name: Install dependencies
-      run: pip install -U tox codecov
-    - name: Run Tox
-      run: tox -e du-latest -- -vv

.github/workflows/main.yml

@@ -25,6 +25,7 @@ jobs:
         docutils:
         - "du18"
         - "du19"
+        - "du-latest"
 
     steps:
     - uses: actions/checkout@v3

tox.ini

@@ -1,6 +1,6 @@
 [tox]
 minversion = 2.4.0
-envlist = docs,flake8,mypy,twine,py{38,39,310,311,312},du{18,19}
+envlist = docs,flake8,mypy,twine,py{38,39,310,311,312},du{18,19,-latest}
 isolated_build = True
 
 [testenv]
@@ -19,9 +19,11 @@ passenv =
 description =
     py{38,39,310,311,312}: Run unit tests against {envname}.
     du{18,19}: Run unit tests with the given version of docutils.
+    du-latest: Run unit tests with Docutils' HEAD
 deps =
     du18: docutils==0.18.*
     du19: docutils==0.19.*
+    du-latest: git+https://repo.or.cz/docutils.git#subdirectory=docutils
 extras =
     test
 setenv =
@@ -30,11 +32,6 @@ setenv =
 commands=
     python -X dev -X warn_default_encoding -m pytest --durations 25 {posargs}
 
-[testenv:du-latest]
-commands =
-    python -m pip install "git+https://repo.or.cz/docutils.git#subdirectory=docutils" --no-warn-conflicts
-    {[testenv]commands}
-
 [testenv:flake8]
 basepython = python3
 description =