Replace pandas with scikit-spectra

[DancingQuanta]

Hi, I wanted to bring your attention to this library scikit-spectra. No idea if you were aware of this library.

The library provide modified pandas.series/dataframe with additional functionality such as wavelength unit conversions, normalisation and others.
The strength of specdal is bundling the metadata of the instrument with the spectrum and I like to help with this marriage if scikit-spectra meets your objectives.