API reference for unit annotations on dataclasses (e.g. `EbtelResult`) do not render nicely

The way dataclasses handle type/unit annotations must have changed in Python 3.12 because the API documentation no longer renders the unit annotations correctly, e.g. https://ebtelplusplus.readthedocs.io/en/latest/api/ebtelplusplus.EbtelResult.html#ebtelplusplus.EbtelResult.tr_corona_radiative_loss_ratio. Furthermore, the docs build on GitHub Actions is now failing because of a warning about an unfound reference for u.dimensionless_unscaled.

This should be addressed before a new release is cut.