Don't install Python codecov package (not used)

Author: takluyver

.github/workflows/main.yml

@@ -47,7 +47,7 @@ jobs:
       run: |
         python -m pip install --upgrade pip
         pip install -e .[test]
-        pip install tox coverage codecov tox-gh-actions
+        pip install tox coverage tox-gh-actions
     - name: Run the tests
       run: tox
     - name: Upload coverage to Codecov