No longer test against casatools and casatasks

[astrofrog]

... since spectral-cube now depends on casa-formats-io by default

Fixes #65

[codecov]

Codecov Report

Merging #66 (1067dc0) into main (b0c598c) will increase coverage by 0.34%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main      #66      +/-   ##
==========================================
+ Coverage   96.13%   96.48%   +0.34%     
==========================================
  Files          15       15              
  Lines        1139     1137       -2     
==========================================
+ Hits         1095     1097       +2     
+ Misses         44       40       -4     

Impacted Files	Coverage Δ
...onomy/io/spectral_cube/tests/test_spectral_cube.py	100.00% <100.00%> (+10.81%)	⬆️

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[dhomeier]

Has the interface/format changed from casatools to casa-formats-io?

            if os.path.isdir(datafn):
>               raise OSError("Tried to access a data file that's actually "
E               OSError: Tried to access a data file that's actually a package data directory

cube_3d.image does not look like any standard format, but I currently cannot access any pkg_data files under data/ (getting a 404 from two different IPs here), so cannot check.

[dhomeier]

if os.path.isdir(datafn):
>               raise OSError("Tried to access a data file that's actually "
E               OSError: Tried to access a data file that's actually a package data directory

Ah, it's get_pkg_data_filename itself stumbling on this:
https://github.com/glue-viz/glue-astronomy/pull/64/files#r814350245
@pllim is there any trick to work around this using, say get_pkg_data_filenames (plural!) or get_pkg_data_path? Both seem to be able to retrieve the local path in tests/data, but I suppose they will not take care of the automatic remote retrieval?

[pllim]

I still don't like this. See #62

[pllim]

@astrofrog , @dhomeier , see astrofrog#1 (PR to this PR)