Codecov is not being updated

[veenstrajelmer]

HydroMT version checks

• I have checked that this issue has not already been reported.
• I have checked that this bug exists on the latest version of HydroMT.

Reproducible Example

Current behaviour

Codecov is not being called, the latest status is a year old

Desired behaviour

This should be added to tests.yml:

    - uses: codecov/codecov-action@v4
      env:
        CODECOV_TOKEN: ${{secrets.CODECOV_TOKEN}}

Additional context

The token is required by the Deltares organization