Fix: Update GitHub Actions workflow for Python testing

- I updated actions/checkout to v4 and actions/setup-python to v5.
- I modified CI to install tox and run tests using 'tox -e py'.
- This change aims to resolve issues with Python version availability in the CI environment, particularly for Python 3.8.
- The Python version matrix in the CI ('3.8', '3.9', '3.10', '3.11', '3.12') remains aligned with tox.ini.

Author: google-labs-jules[bot]

.github/workflows/testing.yml

@@ -14,22 +14,20 @@ jobs:
         python-version: ['3.8', '3.9', '3.10', '3.11', '3.12']
 
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v4
     - name: Set up Python ${{ matrix.python-version }}
-      uses: actions/setup-python@v1
+      uses: actions/setup-python@v5
       with:
         python-version: ${{ matrix.python-version }}
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip
-        pip install -r requirements.txt
-        pip install -r requirements-tests.txt
+        pip install tox
     - name: Lint with flake8
       run: |
         flake8 . --count --select=E9,F63,F7,F82 --show-source --statistics
         flake8 . --count --exit-zero --max-complexity=10 --max-line-length=127 --statistics
-    - name: Test with pytest
+    - name: Test with tox
       env:
         COVERALLS_REPO_TOKEN: ${{ secrets.COVERALLS_REPO_TOKEN }}
-      run: |
-        pytest
+      run: tox -e py