Attempt to add coverage action

.github/workflows/tests.yaml

@@ -34,4 +34,7 @@ jobs:
           pip install -r requirements-dev.txt
 
       - name: Test
-        run: pytest tests -s -v --color=yes
+        run: pytest --color=yes --cov --cov-report=xml --cov-report=term-missing
+
+      - name: Coverage
+        uses: codecov/codecov-action@v3