updated test requirements

.github/workflows/python-tests.yml

@@ -33,7 +33,7 @@ jobs:
           python -m pip install .
     - name: Install Test dependencies
       run: |
-        python -m pip install pytest coverage flake8
+        python -m pip install pytest coverage flake8, pytest-cov
     - name: Lint with flake8
       run: |
         # stop the build if there are Python syntax errors or undefined names