Revert to Ubuntu 20.04 again – Ubuntu 22.04 has a minimum Python 3.8 …

…version of 3.8.12, while Windows has a maximum of 3.8.10.

.github/actions/setup-python/action.yml

@@ -20,7 +20,7 @@ runs:
         # runner versions.
         python-version: |
           3.7
-          3.8.15
+          3.8.10
           3.9
           3.10
           3.11

.github/workflows/ci.yml

@@ -14,7 +14,7 @@ defaults:
 jobs:
 
   product:
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-20.04
     steps:
       - uses: smorimoto/tune-github-hosted-runner-network@v1.0.0
       - uses: actions/checkout@v4.1.6
@@ -72,7 +72,7 @@ jobs:
 
 
   docs:
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-20.04
     steps:
       - uses: smorimoto/tune-github-hosted-runner-network@v1.0.0
       - uses: actions/checkout@v4.1.6
@@ -103,7 +103,7 @@ jobs:
 
 
   gradlePython:
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-20.04
     steps:
       - uses: smorimoto/tune-github-hosted-runner-network@v1.0.0
       - uses: actions/checkout@v4.1.6
@@ -120,7 +120,7 @@ jobs:
 
   demo:
     needs: [product]
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-20.04
     steps:
       - uses: smorimoto/tune-github-hosted-runner-network@v1.0.0
       - uses: actions/checkout@v4.1.6
@@ -163,7 +163,7 @@ jobs:
           # Runners must support all the Python versions in setup-python/action.yml: see
           # https://github.com/actions/python-versions/blob/main/versions-manifest.json.
           - os: linux
-            runs-on: ubuntu-22.04
+            runs-on: ubuntu-20.04
           - os: macos
             runs-on: macos-12
           - os: windows

product/gradle-plugin/README.md

@@ -96,6 +96,7 @@ After stable release:
 
 * Update `MAX_BUILD_PYTHON_VERSION` in test_gradle_plugin.py, and run the tests which
   use it.
+* Run `gradle:testPython`.
 * Update the list of Python versions in .github/actions/setup-python/action.yml.
 * Build the demo app with the new version, and check for any warnings other than the
   expected ones about .pyc compilation.