Deprecation of the Regions parser

[bennahugo]

Need to fix:

WARNING: AstropyDeprecationWarning: The DS9Parser class is deprecated and may be removed in a future version.
        Use `regions.Regions.parse` instead. [cubical.degridder.DicoSourceProvider]
WARNING:astropy:AstropyDeprecationWarning: The DS9Parser class is deprecated and may be removed in a future version.
        Use `regions.Regions.parse` instead.

[o-smirnov]

Yeah I just moved breizorro to regions, it's simple: https://github.com/ratt-ru/breizorro/blob/main/breizorro/breizorro.py#L226

[bennahugo]

will change to regions.Regions.read(filename) which may autodetect the format from the magic string as discussed. The .parse does not for some reason - at least not in the last release version for python 3.6

[bennahugo]

done