Coloraide-extras

- **NEW**: Drop Python 3.8.
- **NEW**: Require ColorAide 4.3.
- **NEW**: Add spectral interpolation that leverages Kubelka-Munk theory for color mixing.

- **NEW**: Officially support Python 3.13.
- **NEW**: Require ColorAide 4.0.

- **NEW**: Officially support Python 3.12.

- **NEW**: Drop Python 3.7.
- **NEW**: CIE 1960 UCS moved to official ColorAide repository.

- **NEW**: All CAM16 related spaces, and distancing plugins moved to official ColorAide.
- **NEW**: All HCT related spaces, gamut mapping, distancing, and contrast plugins moved to official ColorAide.