Pye3d

- Automated Python wheels for Python 3.6 - 3.9 on Linux, macOS, and Windows

- Simplification of ``Conic`` parameter calculation - 26
- Incremental performance improvements - 27
- Correctly apply corneal-refraction correction to ``diameter_3d`` result - 28

- Expose 3d eye model RMS fitting residuals; disable them by default - 24

- Pin ``scikit-learn==0.24.1`` version and update refraction models to that version -
Avoids warning when unpickling refraction pipeline
- Replace all occurances of ``np.float`` with ``float`` - ``np.float`` has been
`deprecated <https://numpy.org/devdocs/release/1.20.0-notes.html#deprecations>`_.
- Stop treating all warnings in `pye3d/cpp/projections.pyx:unproject_ellipse()` as
errors - The previous behavior was introduced to avoid repeated division-by-zero errors.
The new implementation continues to handle these as errors but excludes other types of
warnings, e.g. ``DeprecationWarning``, from this handling.