diff --git a/.github/actions/setup-python/action.yml b/.github/actions/setup-python/action.yml
index e34e40ae46..29b3feb07e 100644
--- a/.github/actions/setup-python/action.yml
+++ b/.github/actions/setup-python/action.yml
@@ -1,30 +1,28 @@
 name: Setup Python
 description:
 
-inputs:
-  extra-versions:
-    description: |
-      Additional versions to install, on top of the supported runtime versions. One
-      version per line, in the same syntax as the standard setup-python action.
-
 runs:
   using: composite
   steps:
-    - name: List runtime versions
-      id: runtime-versions
-      shell: bash
-      run: |
-        (
-            echo "versions<<EOF"
-            target/list-versions.py --minor
-            echo EOF
-        ) >> $GITHUB_OUTPUT
-
     - uses: actions/setup-python@v4.6.1
       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.
         python-version: |
-          ${{ steps.runtime-versions.outputs.versions }}
-          ${{ inputs.extra-versions }}
+          3.6
+          3.7
+          3.8.10
+          3.9
+          3.10
+          3.11
+          3.12
 
     - name: Set default Python command
       id: python-default
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 8db1d5fd35..69e5b2e43b 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -14,7 +14,7 @@ defaults:
 jobs:
 
   product:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
     steps:
       - uses: smorimoto/tune-github-hosted-runner-network@v1
       - uses: actions/checkout@v3.5.3
@@ -72,7 +72,7 @@ jobs:
 
 
   docs:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
     steps:
       - uses: smorimoto/tune-github-hosted-runner-network@v1
       - uses: actions/checkout@v3.5.3
@@ -103,15 +103,12 @@ jobs:
 
 
   gradlePython:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
     steps:
       - uses: smorimoto/tune-github-hosted-runner-network@v1
       - uses: actions/checkout@v3.5.3
 
-      - uses: actions/setup-python@v4.6.1
-        with:
-          # MIN_BUILD_PYTHON_VERSION from test_gradle_plugin
-          python-version: 3.7
+      - uses: ./.github/actions/setup-python
 
       - uses: ./.github/actions/create-local-properties
 
@@ -123,7 +120,7 @@ jobs:
 
   demo:
     needs: [product]
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
     steps:
       - uses: smorimoto/tune-github-hosted-runner-network@v1
       - uses: actions/checkout@v3.5.3
@@ -163,9 +160,8 @@ jobs:
         agp-version: ${{ fromJSON(needs.product.outputs.agp-versions) }}
         os: [linux, macos, windows]
         include:
-          # We pin specific OS versions to ensure that the Python `extra-versions`
-          # listed below are all available. To avoid clutter in the GitHub UI, OS
-          # versions are not added to the `os` dimension directly.
+          # To avoid clutter in the GitHub UI, OS versions are not added to the `os`
+          # dimension directly.
           - os: linux
             runs-on: ubuntu-20.04
           - os: macos
@@ -180,13 +176,6 @@ jobs:
 
       - uses: ./.github/actions/setup-python
         id: setup-python
-        with:
-          # This should include OLD_BUILD_PYTHON_VERSION, MIN_BUILD_PYTHON_VERSION and
-          # MAX_BUILD_PYTHON_VERSION from test_gradle_plugin, if they're not already
-          # returned by `list-versions.py --minor`.
-          extra-versions: |
-            3.6
-            3.7
 
       - name: Download Maven repository
         uses: actions/download-artifact@v3.0.2
diff --git a/product/gradle-plugin/README.md b/product/gradle-plugin/README.md
index 3af390f02a..b9d7865b28 100644
--- a/product/gradle-plugin/README.md
+++ b/product/gradle-plugin/README.md
@@ -95,6 +95,7 @@ After stable release:
 
 * Update `MAX_BUILD_PYTHON_VERSION` in test_gradle_plugin.py, and run the tests which
   use it.
+* 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.
 
@@ -105,8 +106,7 @@ After stable release:
 * Update `testPython` in gradle-plugin/build.gradle, and run the tests.
 * In test_gradle_plugin, update `OLD_BUILD_PYTHON_VERSION` and
   `MIN_BUILD_PYTHON_VERSION`, and run the tests which use them.
-* Check references to `OLD_BUILD_PYTHON_VERSION` and `MIN_BUILD_PYTHON_VERSION` in
-  ci.yml.
+* Update the list of Python versions in .github/actions/setup-python/action.yml.
 * Update android.rst.
 
 
diff --git a/product/gradle-plugin/src/test/integration/test_gradle_plugin.py b/product/gradle-plugin/src/test/integration/test_gradle_plugin.py
index 1013f3577c..e490d223ea 100644
--- a/product/gradle-plugin/src/test/integration/test_gradle_plugin.py
+++ b/product/gradle-plugin/src/test/integration/test_gradle_plugin.py
@@ -65,7 +65,7 @@ def list_versions(mode):
                              .split()[1])
 BUILD_PYTHON_VERSION = BUILD_PYTHON_VERSION_FULL.rpartition(".")[0]
 
-# When updating these, consider also updating extra-versions in ci.yml.
+# When updating these, consider also updating .github/actions/setup-python/action.yml.
 OLD_BUILD_PYTHON_VERSION = "3.6"
 MIN_BUILD_PYTHON_VERSION = "3.7"
 MAX_BUILD_PYTHON_VERSION = "3.12"