Update python-app.yml

Author: AlecThomson

.github/workflows/python-app.yml

@@ -37,6 +37,7 @@ jobs:
     - name: Lint with black
       run: |
         black --check arrakis
-#     - name: Test with pytest
-#       run: |
-#         pytest
+    - name: Upload coverage reports to Codecov
+      uses: codecov/codecov-action@v3
+      env:
+        CODECOV_TOKEN: ${{ secrets.CODECOV_TOKEN }}