MAINT: Resolve warnings of Logger library

[emmanuel-ferdman]

PR Summary

This PR resolves the deprecation warnings of the logger library:

DeprecationWarning: The 'warn' method is deprecated, use 'warning' instead

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 1 line in your changes missing coverage. Please review.

Project coverage is 69.88%. Comparing base (823e49f) to head (43a0c98).
Report is 9 commits behind head on main.

Files with missing lines	Patch %	Lines
astroquery/gaia/core.py	0.00%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3316   +/-   ##
=======================================
  Coverage   69.88%   69.88%           
=======================================
  Files         232      232           
  Lines       19761    19761           
=======================================
  Hits        13810    13810           
  Misses       5951     5951           

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[bsipocz]

Thanks!