fix coverage report upload (#152)

Author: mathause

.github/workflows/ci.yaml

@@ -74,7 +74,6 @@ jobs:
       env:
         CODECOV_TOKEN: ${{ secrets.CODECOV_TOKEN }}
       with:
-          file: ./coverage.xml
           flags: unittests
           env_vars: RUNNER_OS,PYTHON_VERSION
           name: codecov-umbrella