Build docs on 3.11 & dedup

.github/workflows/ci.yml

@@ -172,8 +172,8 @@ jobs:
           workflow-artifact-name: ${{ env.sdist-artifact }}
       - uses: actions/setup-python@v4
         with:
-          # Keep in sync with noxfile.py/docs & .readthedocs.yaml
-          python-version: "3.10"
+          # Keep in sync with .readthedocs.yaml
+          python-version: "3.11"
       - run: python -Im pip install --upgrade wheel nox
 
       - run: python -Im nox -e docs

.readthedocs.yaml

@@ -4,8 +4,8 @@ version: 2
 build:
   os: ubuntu-20.04
   tools:
-    # Keep in sync with noxfile.py/tests_oldestAttrs & ci.yml/docs
-    python: "3.10"
+    # Keep in sync with ci.yml/docs
+    python: "3.11"
 
 python:
   install:

noxfile.py

@@ -1,6 +1,9 @@
 from __future__ import annotations
 
 import os
+import re
+
+from pathlib import Path
 
 import nox
 
@@ -9,6 +12,14 @@
 nox.options.error_on_external_run = True
 
 
+MATCH_PYTHON = re.compile(r"\s+python\: \"(\d\.\d\d)\"").match
+# Avoid dependency on a YAML lib using a questionable hack.
+for line in Path(".readthedocs.yaml").read_text().splitlines():
+    if m := MATCH_PYTHON(line):
+        DOCS_PYTHON = m.group(1)
+        break
+
+
 @nox.session
 def pre_commit(session: nox.Session) -> None:
     session.install("pre-commit")
@@ -60,8 +71,7 @@ def mypy(session: nox.Session) -> None:
     session.run("mypy", "typing_examples.py")
 
 
-# Keep python in sync with ci.yml/docs and .readthedocs.yaml.
-@nox.session(python="3.10")
+@nox.session(python=DOCS_PYTHON)
 def docs(session: nox.Session) -> None:
     session.install(".[docs]")