use tox as test-runner

.github/workflows/testing.yml

@@ -1,7 +1,7 @@
 # This workflow will install Python dependencies, run tests and lint with a variety of Python versions
 # For more information see: https://help.github.com/actions/language-and-framework-guides/using-python-with-github-actions
 
-name: Package Testing
+name: Package Testing with Tox
 
 on:
   push:
@@ -23,11 +23,7 @@ jobs:
       uses: actions/setup-python@v1
       with:
         python-version: ${{ matrix.python-version }}
-    - name: Install dependencies
-      run: |
-        python -m pip install --upgrade pip
-        pip install -r requirements.txt
-    - name: Test with pytest
-      run: |
-        pip install pytest
-        pytest
+    - name: Install Tox and any other packages
+      run: pip install tox
+    - name: Run Tox
+      run: tox -e py  # Run tox using the version of Python in `PATH`