Stop using setup-python

And de-dup docs Python version handling.

Author: hynek

.github/workflows/ci.yml

@@ -50,10 +50,6 @@ jobs:
         run: |
           tar xf dist/*.tar.gz --strip-components=1
           rm -rf src
-      - uses: actions/setup-python@v5
-        with:
-          python-version: ${{ matrix.python-version }}
-          allow-prereleases: true
       - uses: hynek/setup-cached-uv@v2
 
       - name: Prepare & run Nox
@@ -86,9 +82,6 @@ jobs:
       - uses: actions/checkout@v4
         with:
           persist-credentials: false
-      - uses: actions/setup-python@v5
-        with:
-          python-version-file: .python-version-default
       - uses: hynek/setup-cached-uv@v2
 
       - uses: actions/download-artifact@v4
@@ -98,7 +91,7 @@ jobs:
 
       - name: Combine coverage & fail if it's <100%.
         run: |
-          uv tool install coverage
+          uv tool install --python $(cat .python-version-default) coverage
 
           coverage combine
           coverage html --skip-covered --skip-empty
@@ -134,10 +127,6 @@ jobs:
           name: Packages
           path: dist
       - run: tar xf dist/*.tar.gz --strip-components=1
-      - uses: actions/setup-python@v5
-        with:
-          python-version: ${{ matrix.python-version }}
-          allow-prereleases: true
       - uses: hynek/setup-cached-uv@v2
 
       - name: Check using Mypy
@@ -168,13 +157,14 @@ jobs:
           name: Packages
           path: dist
       - run: tar xf dist/*.tar.gz --strip-components=1
-      - uses: actions/setup-python@v5
-        with:
-          python-version-file: .python-version-default
       - uses: hynek/setup-cached-uv@v2
 
       - name: Prepare & run Nox
-        run: uvx nox --sessions mypy_pkg
+        run: >
+          uvx
+          --python $(cat .python-version-default)
+          nox
+          --sessions mypy_pkg
 
   docs:
     name: Run doctests
@@ -187,10 +177,6 @@ jobs:
           name: Packages
           path: dist
       - run: tar xf dist/*.tar.gz --strip-components=1
-      - uses: actions/setup-python@v5
-        with:
-          # Keep in sync with .readthedocs.yaml
-          python-version: "3.13"
       - uses: hynek/setup-cached-uv@v2
 
       - name: Prepare & run Nox
@@ -207,14 +193,11 @@ jobs:
       - uses: actions/checkout@v4
         with:
           persist-credentials: false
-      - uses: actions/setup-python@v5
-        with:
-          python-version-file: .python-version-default
       - uses: hynek/setup-cached-uv@v2
 
       - name: Install in dev mode
         run: |
-          uv venv
+          uv venv --python $(cat .python-version-default)
           uv pip install -e .[dev]
 
       - name: Try to import on Linux

.readthedocs.yaml

@@ -4,7 +4,6 @@ version: 2
 build:
   os: ubuntu-lts-latest
   tools:
-    # Keep version in sync with tox.ini/docs and ci.yml/docs.
     python: "3.13"
   jobs:
     create_environment:

noxfile.py

@@ -6,6 +6,7 @@
 
 import os
 import pathlib
+import re
 import shutil
 import sys
 
@@ -39,6 +40,12 @@
     if pv.startswith("Programming Language :: Python :: ")
 ]
 
+DOCS_PYTHON = re.search(
+    r'^ +python: "(3\.13)"$',
+    pathlib.Path(".readthedocs.yaml").read_text(),
+    flags=re.MULTILINE,
+).group(1)
+
 
 @nox.session
 def pre_commit(session: nox.Session) -> None:
@@ -107,7 +114,7 @@ def coverage_report(session: nox.Session) -> None:
     session.run("coverage", "report")
 
 
-@nox.session
+@nox.session(python=DOCS_PYTHON)
 def docs(session: nox.Session) -> None:
     shutil.rmtree("docs/_build", ignore_errors=True)