action: use the most recent python from tool cache to run the GitHub Action

.github/workflows/test.yml

@@ -37,7 +37,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [ubuntu-latest, windows-latest, macos-11]
+        os: [ubuntu-18.04, windows-latest, macos-11]
         python_version: ['3.10']
     timeout-minutes: 180
     steps:
@@ -63,21 +63,21 @@ jobs:
       run: |
         python -m pip install ".[test]"
 
-    - name: Sample build
-      if: "contains(github.event.pull_request.labels.*.name, 'CI: Sample build')"
-      run: |
-        python bin/sample_build.py
-
-    - name: Get some sample wheels
+    - name: Generate a sample project
       run: |
         python -m test.test_projects test.test_0_basic.basic_project sample_proj
-        cibuildwheel --output-dir wheelhouse sample_proj
+
+    - name: Run a sample build (GitHub Action)
+      uses: ./
+      with:
+        package-dir: sample_proj
+        output-dir: wheelhouse
       env:
         CIBW_ARCHS_MACOS: x86_64 universal2 arm64
 
     - uses: actions/upload-artifact@v3
       with:
-        name: sample_wheels
+        name: sample_wheels_action
         path: wheelhouse
 
     - name: Test cibuildwheel

action.yml

@@ -20,10 +20,17 @@ branding:
 runs:
   using: composite
   steps:
+    # Set up a non-EOL, cibuildwheel & pipx supported Python version
+    - uses: actions/setup-python@v4
+      id: python
+      with:
+        python-version: "3.7 - 3.10"
+        update-environment: false
 
     # Redirecting stderr to stdout to fix interleaving issue in Actions.
     - run: >
         pipx run
+        --python '${{ steps.python.outputs.python-path }}'
         --spec '${{ github.action_path }}'
         cibuildwheel
         ${{ inputs.package-dir }}