fix pkg_resources, scipy.ndimage, and pytest deprecation warnings

[moustakas]

This PR cleans up a number of deprecation warnings seen in the unit tests due to:

• pkg_resources.resource_filename (deprecated in favor of importlib.resources.files; see also use Importlib.resources instead of (deprecated and slower) pkg resources.resource_filename desispec#2157))
• scipy.ndimage; and
• pytest (deprecated test_suite functions).

The pkg_resources warnings aren't seen in the desitarget tests because tests are only done against python/3.9, but they are seen in other packages like fastspecfit, which are testing against python/3.10 and 3.11.

[coveralls]

coverage: 53.047% (-0.003%) from 53.05%
when pulling 47d5429 on fix-deprecation-warnings
into 971d9d5 on main.

[moustakas]

@geordie666 I accidentally updated doc/changes.rst in main (while belatedly checking to make sure I had the most recent commits), but then made the same change here. Let me know if you want me to fix main (sorry!).

Also, coverage tests are failing (not just here, but for some time), but I'm not sure why.

[geordie666]

Excellent, thanks for these updates. Reviewing now. I don't think it's an issue that you updated changes.rst in main. That doc file is always easy to merge/revert.

[geordie666]

I think everything looks good @moustakas, and only have one suggestion/request:

Could you change constructions like this (there are quite a few so I didn't want to flag them all):

cmd = resources.files('desitarget').joinpath('urat/fortran/v1dump')

to use os.path.join() or something similar? I know that we mostly only support nix-like operating systems in desitarget but it's conceivable that some functions are useful on other OS's that don't use / as the path separator.

I'm not sure why the coverage tests are failing. It hasn't been a high priority to dig into, but we should open an issue for completeness.

[moustakas]

Could you change constructions like this (there are quite a few so I didn't want to flag them all):
cmd = resources.files('desitarget').joinpath('urat/fortran/v1dump')
to use os.path.join() or something similar? I know that we mostly only support nix-like operating systems in desitarget but it's conceivable that some functions are useful on other OS's that don't use / as the path separator.

@geordie666 I'm sorry to push back, but I think this is unnecessary busy work for me and I don't think I'd prioritize getting to these changes (whereas the deprecation warnings are making it annoying for me to identify genuine errors and other relevant warnings in fastspecfit).

In the spirit of making the minimal set of changes in this PR, I simply inherited the use of / as the path separator currently in desitarget/main, so if we want to make this change, I recommend we open a new ticket and try to make these changes in a different PR.

Hope that's alright.

[geordie666]

That's fine. Go ahead and merge. I'll do the busywork in my next branch.