try fix python version restriction on tests, add optional cache clearing to CI

Author: bckohan

.github/workflows/test.yml

@@ -14,6 +14,11 @@ on:
         required: true
         default: false
         type: boolean
+      clear_cache:
+        description: 'Clear GitHub Actions cache.'
+        required: true
+        default: false
+        type: boolean
 jobs:
   linux:
     runs-on: ubuntu-latest
@@ -27,6 +32,10 @@ jobs:
       COVERAGE_FILE: linux-py${{ matrix.python-version }}.coverage
 
     steps:
+    - name: Clear GitHub Actions cache
+      if: ${{ github.event.inputs.clear_cache == 'true' }}
+      run: sudo rm -rf /opt/hostedtoolcache
+  
     - uses: actions/checkout@v4
     - name: Set up Python ${{ matrix.python-version }}
       id: sp
@@ -79,6 +88,7 @@ jobs:
 
     steps:
     - name: Clear GitHub Actions cache
+      if: ${{ github.event.inputs.clear_cache == 'true' }}
       run: sudo rm -rf /Users/runner/hostedtoolcache
 
     - uses: actions/checkout@v4
@@ -132,6 +142,9 @@ jobs:
       COVERAGE_FILE: windows-py${{ matrix.python-version }}.coverage
 
     steps:
+    - name: Clear GitHub Actions cache
+      if: ${{ github.event.inputs.clear_cache == 'true' }}
+      run: Remove-Item -Recurse -Force C:\hostedtoolcache
     - uses: actions/checkout@v4
     - name: Set up Python ${{ matrix.python-version }}
       id: sp

tests/examples/test_examples.py

@@ -41,10 +41,12 @@ def test_howto_symmetry():
     from tests.examples import howto_symmetry
 
 
+@pytest.mark.skipif(sys.version_info < (3, 10), reason="requires Python 3.10 or higher")
 def test_howto_symmetric_overload():
     from tests.examples import howto_symmetric_overload
 
 
+@pytest.mark.skipif(sys.version_info < (3, 11), reason="requires Python 3.11 or higher")
 def test_howto_verify_unique():
     with pytest.raises(ValueError):
         from tests.examples import howto_verify_unique