^ci: add more python versions to test matrix

.github/workflows/pythonapp.yml

@@ -12,7 +12,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python-version: [3.7, 3.8, 3.9]
+        python-version: [3.8, 3.9, '3.10', '3.11']
 
     steps:
     - uses: actions/checkout@v3
@@ -20,6 +20,7 @@ jobs:
       uses: actions/setup-python@v4
       with:
         python-version: ${{ matrix.python-version }}
+        cache: pip
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip