diff --git a/.github/actions/setup-python/action.yml b/.github/actions/setup-python/action.yml
index 701d125a79..6fcadf184e 100644
--- a/.github/actions/setup-python/action.yml
+++ b/.github/actions/setup-python/action.yml
@@ -1,26 +1,37 @@
 name: Setup Python
 description:
 
+# When updating this file, see the comment in ci.yml about integration test
+# runner versions.
 runs:
   using: composite
   steps:
+    # For the default Python version, the micro version should be different to the
+    # one used by the runtime, because that's required by the integration tests
+    # `requires_python` and `marker_python_version`. For all other versions, we let
+    # the GitHub runner pick a micro version, which will be faster because it's
+    # locally cached.
+    - name: Get default Python version
+      id: python-default
+      shell: bash
+      run: |
+        version=3.8
+        if [ $RUNNER_OS = Windows ]; then
+            echo "command=py -$version"
+            echo "version=3.8.10"
+        else
+            echo "command=python$version"
+            echo "version=3.8.12"
+        fi >> $GITHUB_OUTPUT
+
     - uses: actions/setup-python@v5.1.0
       with:
         # This should include all major.minor versions supported by the runtime, plus
         # OLD_BUILD_PYTHON_VERSION, MIN_BUILD_PYTHON_VERSION and
         # MAX_BUILD_PYTHON_VERSION from test_gradle_plugin.
-        #
-        # For the default Python version, the micro version should be different to the
-        # one used by the runtime, because that's required by the integration tests
-        # `requires_python` and `marker_python_version`. For all other versions, we let
-        # the GitHub runner pick a micro version, which will be faster because it's
-        # locally cached.
-        #
-        # When updating this list, see the comment in ci.yml about integration test
-        # runner versions.
         python-version: |
           3.7
-          3.8.10
+          ${{ steps.python-default.outputs.version }}
           3.9
           3.10
           3.11
@@ -28,17 +39,6 @@ runs:
           3.13
         allow-prereleases: true
 
-    - name: Set default Python command
-      id: python-default
-      shell: bash
-      run: |
-        version=$(target/list-versions.py --default)
-        if [ $RUNNER_OS = Windows ]; then
-            echo "command=py -$version"
-        else
-            echo "command=python$version"
-        fi >> $GITHUB_OUTPUT
-
 outputs:
   python-default:
     description: Command to run the default Python version
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index ac226a46de..0f029a6e0f 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -14,7 +14,7 @@ defaults:
 jobs:
 
   product:
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
     steps:
       - uses: smorimoto/tune-github-hosted-runner-network@v1.0.0
       - uses: actions/checkout@v4.1.6
@@ -73,7 +73,7 @@ jobs:
 
 
   docs:
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
     steps:
       - uses: smorimoto/tune-github-hosted-runner-network@v1.0.0
       - uses: actions/checkout@v4.1.6
@@ -105,7 +105,7 @@ jobs:
 
 
   gradlePython:
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
     steps:
       - uses: smorimoto/tune-github-hosted-runner-network@v1.0.0
       - uses: actions/checkout@v4.1.6
@@ -123,7 +123,7 @@ jobs:
 
   demo:
     needs: [product]
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
     steps:
       - uses: smorimoto/tune-github-hosted-runner-network@v1.0.0
       - uses: actions/checkout@v4.1.6
@@ -166,7 +166,7 @@ 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-20.04
+            runs-on: ubuntu-22.04
           - os: macos
             runs-on: macos-13
           - os: windows
diff --git a/target/README.md b/target/README.md
index 1df3846d6d..809f442315 100644
--- a/target/README.md
+++ b/target/README.md
@@ -72,7 +72,6 @@ Update the Python version in all apps in the repository.
 
 Update the pythonX.Y scripts in integration/data/BuildPython.
 
-See the note about the default Python micro version in
-.github/actions/setup-python/action.yml.
+Update .github/actions/setup-python/action.yml.
 
 (REST OF LIST TBD)