[MRG] Update wrapper for new geomloss version

[rflamary]

Types of changes

• Use the new geomloss unified API in ot.solve_sample
• Make dual potential and plan computation optional (only when log=True) in empirical_sinkhorn2_geomloss because using grad prevent performing backward on the loss.
• Update of the labeler to take into account new folder modules

It works well but it might surprise users because it is a thin wrapper around solve_sample that returns a geomloss OTResultSample that is still a little different (See API Issues 91 92 ).

More important questio is the detached weight in the current version discussed here

Motivation and context / Related issue

How has this been tested (if it applies)

PR checklist

• I have read the CONTRIBUTING document.
• The documentation is up-to-date with the changes I made (check build artifacts).
• All tests passed, and additional code has been covered with new tests.
• I have added the PR and Issue fix to the RELEASES.md file.

[codecov]

Codecov Report

❌ Patch coverage is 88.88889% with 6 lines in your changes missing coverage. Please review.
✅ Project coverage is 96.79%. Comparing base (6c98fac) to head (164fa3d).

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #826      +/-   ##
==========================================
- Coverage   96.80%   96.79%   -0.01%     
==========================================
  Files         127      127              
  Lines       25136    25149      +13     
==========================================
+ Hits        24333    24344      +11     
- Misses        803      805       +2     

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