Support for frequency extrapolation, new solar irradiance models, and better performance using `quadpy`

This release introduces a new features and improves the performance of the Zodipy by using the quadpy library to perform vectorized line of sight integration.

[0.5.6] - 2022-04-19

• Added possibility to select between modern solar irradiance models for computing the scattered solar emission. These can be selected by specifying the solar_irradiance_model argument when initializing Zodipy.
• Zodipy now throws an error by default if the selected frequency or wavelength is outside of the range covered by the selected interplanetary dust model. To linearly extrapolate the spectral parameters in the model, set extarpolate=True when initializing Zodipy.
• Improved performance is achieved by introducing quadpy as a new dependency, which speeds up the line of sight integration.