don't install tox-gh-actions for coverage

Author: basnijholt

.github/workflows/coverage.yml

@@ -15,7 +15,7 @@ jobs:
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip
-        pip install tox tox-gh-actions codecov
+        pip install tox codecov
     - name: Test with tox
       run: tox -e py37-alldeps-linux,report
     - name: Upload test coverage