[Documentation] `perez_driesse` is missing in `ValueError` definition of `pvlib.irradiation.get_sky_diffuse`

[BernatNicolau]

Describe the bug
In the ValueError definition of get_sky_diffuse, perez_driesse seems to be missing.

ValueError
        If model is one of ``'haydavies'``, ``'reindl'``, or ``'perez'`` and
        ``dni_extra`` is not specified.

Should be

ValueError
        If model is one of ``'haydavies'``, ``'reindl'``, ``'perez'``  or
        ``'perez_driesse'`` and ``dni_extra`` is not specified.