write test for distance warning

[dkrako]

During tests a warning is raised for specifying both experiment.screen.distance_cm and a distance column.

We are treating warnings as errors from now on and need to get rid of the ignore in pyproject.toml

• [x] write test for warning
• [x] remove ignore from pyproject.toml

Here is the ignore line in https://github.com/aeye-lab/pymovements/blob/417a305566646de08306a8682a9331e1c5f9ccae/pyproject.toml#L134