Added step to run tests using pytest with extensions

This step runs the pytest command to run the tests using the extensions xdist and pytest-cov

.github/workflows/workflows.yaml

@@ -27,4 +27,8 @@ jobs:
         run: |
           python -m pip install --upgrade pip
           pip install -r requirements.txt
-          pip install -r tests/requirements.txt
+          pip install -r tests/requirements.txt
+      
+      - name: Run tests
+        run: |
+          pytest -n $pytest_cpus --cov-report=xml --cov=$pytest_cov_dir