add codecov to pytest

[veenstrajelmer]

• [x] By adding this to the pytest workflow file. This will enable codecov and that will be visible on this page: https://app.codecov.io/gh/deltares/?search=hydromt

    - name: Test with pytest
      run: |
        pytest -m "not acceptance" --cov=hydromt_delft3dfm --cov-report xml --cov-report term
    - uses: codecov/codecov-action@v1

• [ ] Also, a badge can be added to the readme with:

[![codecov](https://img.shields.io/codecov/c/github/deltares/hydromt_delft3dfm.svg?style=flat-square)](https://app.codecov.io/gh/deltares/hydromt_delft3dfm)

[xldeltares]

The test was successful but with the following error message: {'detail': ErrorDetail(string='Missing "owner" argument. Please upload with the Codecov repository upload token to resolve issue.', code='not_found')}

Potentially helpful post on this issue: https://stackoverflow.com/questions/67861379/codecov-fails-in-github-actions

[veenstrajelmer]

Solved with a minor change, but probably just works because it was the second try of codecov (I've seen the first ones failing more often): https://github.com/Deltares/hydromt_delft3dfm/actions/runs/5451925967/jobs/9918752743

There is now codecov data for the branch: https://app.codecov.io/gh/Deltares/hydromt_delft3dfm/tree/15-fix-tests