MAINT: work around setuptools internals for 80.3

[bsipocz]

Functionality in setuptools got removed without deprecation (pypa/setuptools#4963), and that threw a wrench in our infrastructure, too.

However, there won't be any more helpers released on pypi, so this PR removes the usage of said setuptools functionality as a quick fix while an actual packaging modernization for astroquery is in the works.

(This will only need a changelog if we release before the full refactoring, thus I leave as is; and if needed, I'll add a changelog right before release time.)

The other workaround could be to limit setuptools version, but I'm hopeful that the change will actually be reverted soon and they will do another release.

closes #3309

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 69.87%. Comparing base (bca156d) to head (9d43beb).
⚠️ Report is 208 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3311   +/-   ##
=======================================
  Coverage   69.87%   69.87%           
=======================================
  Files         232      232           
  Lines       19742    19742           
=======================================
  Hits        13795    13795           
  Misses       5947     5947           

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