CDFlib pinned to 0.4.9

[sapols]

CDFlib made a major release 1.0.0 with breaking changes June 2023. It's now up to 1.2.6 as of this writing.

Some PyHC packages don't yet support the new major release so we've pinned the CDFlib version to 0.4.9.

pySPEDAS is the biggest package requiring <1.0.0.
GeospaceLAB is pinned to 0.6.1 because after that it requires >=1.0.0.

[sapols]

Viresclient found a solution to support cdflib before and after the 1.0 release (see this commit):

    @staticmethod
    def _get_attr_or_key(obj, attr):
        # Used to work around cdflib<1 & >=1 support
        # cdflib>=1 introduces dataclasses in place of some dicts
        if isinstance(obj, dict):
            return obj.get(attr, None)
        else:
            return getattr(obj, attr, None)

This is much nicer than how e.g. GeospaceLAB did it, which was to simply switch from the old syntax to the new (hence issue #4). I think PyHC should recommend other packages that use cdflib do the same:

• pySPEDAS (>=0.3.9,<1.0.0) -> (now >=1.2.0)
• PyTplot (any)
• PyTplot-mpl-temp (<1.0.0) -> (now >=1.2.0)
• aidapy (any)
• geospaceLAB (>=0.3.20) -> (now >=1.2.3)
• solo-epd-loader (any)
• themisasi (>=0.3.13)
• viresclient (>=0.3.9)