build: replace outdated *-latest runners with specific ones

This change unlocks the current pipelines because it will allow
use of newer version of 3.9 which is required by tox.

In general is better not to use `-latest` runners because they are
very often outdated versions, causing problems. As github does not
update the name of the runners very often, it is easier to use
specific ones. This also prevents surprises when github is changing
the runner versions as they do this gradually and -latest ones might
point to different runners in different jobs.

Related: tox-dev/tox#3565
Reference: https://github.com/actions/runner-images

Author: ssbarnea

.github/workflows/test.yml

@@ -95,55 +95,55 @@ jobs:
           # Use separate jobs for different unittest flavors (twisted, asynctest) to ensure proper coverage.
           - name: "windows-py39-unittest-asynctest"
             python: "3.9"
-            os: windows-latest
+            os: windows-2025
             tox_env: "py39-asynctest"
             use_coverage: true
 
           - name: "windows-py39-unittest-twisted24"
             python: "3.9"
-            os: windows-latest
+            os: windows-2025
             tox_env: "py39-twisted24"
             use_coverage: true
 
           - name: "windows-py39-unittest-twisted25"
             python: "3.9"
-            os: windows-latest
+            os: windows-2025
             tox_env: "py39-twisted25"
             use_coverage: true
 
           - name: "windows-py39-pluggy"
             python: "3.9"
-            os: windows-latest
+            os: windows-2025
             tox_env: "py39-pluggymain-pylib-xdist"
 
           - name: "windows-py39-xdist"
             python: "3.9"
-            os: windows-latest
+            os: windows-2025
             tox_env: "py39-xdist"
 
           - name: "windows-py310"
             python: "3.10"
-            os: windows-latest
+            os: windows-2025
             tox_env: "py310-xdist"
 
           - name: "windows-py311"
             python: "3.11"
-            os: windows-latest
+            os: windows-2025
             tox_env: "py311"
 
           - name: "windows-py312"
             python: "3.12"
-            os: windows-latest
+            os: windows-2025
             tox_env: "py312"
 
           - name: "windows-py313"
             python: "3.13"
-            os: windows-latest
+            os: windows-2025
             tox_env: "py313"
 
           - name: "windows-py314"
             python: "3.14"
-            os: windows-latest
+            os: windows-2025
             tox_env: "py314"
 
           # Use separate jobs for different unittest flavors (twisted, asynctest) to ensure proper coverage.
@@ -223,28 +223,28 @@ jobs:
 
           - name: "macos-py39"
             python: "3.9"
-            os: macos-latest
+            os: macos-15
             tox_env: "py39-xdist"
             use_coverage: true
 
           - name: "macos-py310"
             python: "3.10"
-            os: macos-latest
+            os: macos-15
             tox_env: "py310-xdist"
 
           - name: "macos-py312"
             python: "3.12"
-            os: macos-latest
+            os: macos-15
             tox_env: "py312-xdist"
 
           - name: "macos-py313"
             python: "3.13"
-            os: macos-latest
+            os: macos-15
             tox_env: "py313-xdist"
 
           - name: "macos-py314"
             python: "3.14"
-            os: macos-latest
+            os: macos-15
             tox_env: "py314-xdist"
 
           - name: "plugins"
@@ -291,17 +291,22 @@ jobs:
         name: Packages
         path: dist
 
-    - name: Set up Python ${{ matrix.python }}
-      uses: actions/setup-python@v5
+    # - name: Set up Python ${{ matrix.python }}
+    #   uses: actions/setup-python@v5
+    #   with:
+    #     python-version: ${{ matrix.python }}
+    #     check-latest: true
+    #     allow-prereleases: true
+
+    - name: Install the latest version of uv
+      uses: astral-sh/setup-uv@v6
       with:
-        python-version: ${{ matrix.python }}
-        check-latest: true
-        allow-prereleases: true
+        version: ${{ matrix.python }}
 
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip
-        pip install tox coverage
+        pip install tox tox-uv coverage
 
     - name: Test without coverage
       if: "! matrix.use_coverage"

.python-version

@@ -0,0 +1,5 @@
+3.9.17
+3.10.13
+3.11.13
+3.12.11
+3.13.5

testing/plugins_integration/requirements.txt

@@ -1,5 +1,6 @@
 anyio[trio]==4.9.0
 django==5.2.1
+pip>=24.0.0
 pytest-asyncio==1.1.0
 pytest-bdd==8.1.0
 pytest-cov==6.2.1

tox.ini

@@ -1,6 +1,8 @@
 [tox]
 isolated_build = True
-minversion = 3.20.0
+minversion = 4.28.1
+requires =
+    tox-uv
 distshare = {homedir}/.tox/distshare
 envlist =
     linting
@@ -159,10 +161,7 @@ setenv =
 description =
     run reverse dependency testing against pytest plugins under `{basepython}`
 # use latest versions of all plugins, including pre-releases
-pip_pre=true
-# use latest pip to get new dependency resolver (#7783)
 download=true
-install_command=python -m pip install {opts} {packages}
 changedir = testing/plugins_integration
 deps = -rtesting/plugins_integration/requirements.txt
 setenv =