Switch to tox for tests (#73)

.github/workflows/python-app.yml

@@ -23,11 +23,7 @@ jobs:
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip
-        pip install flake8==3.8.4 pytest
-        if [ -f requirements.txt ]; then pip install -r requirements.txt; fi
-    - name: Lint with flake8
+        pip install tox
+    - name: Lint and test
       run: |
-        python setup.py lint
-    - name: Test with pytest
-      run: |
-        python setup.py test
+        tox