`pydantic-numpy` isn't listed as a dependency in [pyproject.toml](https://github.com/rom-py/rompy/blob/main/pyproject.toml) but is imported in [`core/spectrum.py`](https://github.com/rom-py/rompy/blob/608905c519ffaec543a2e452cfb15ebdf1a6097c/src/rompy/core/spectrum.py#L6).