consider adopting the fiducial DESI cosmology

[moustakas]

fastphot currently uses a vanilla LCDM cosmology with h=0.7 to compute luminosity distances. Consider adopting the fiducial DESI cosmology to make it easier to map between data and mocks--
https://desi.lbl.gov/trac/wiki/keyprojects#Fiducialcosmology

[moustakas]

Per a suggestion from @ashleyjross, one option would be to move LSS.tabulated_cosmo.TabulatedDESI into fastspecfit (as well as https://github.com/desihub/LSS/blob/main/py/LSS/data/desi_fiducial_cosmology.dat) and then do something like

cosmo = TabulatedDESI()
dis_dc = cosmo.comoving_radial_distance
def dl(z):   # Luminosity distance from now to z
    return dis_dc(z)*(1.+z)

[moustakas]

Done in #96.