Add optional install options with pip

[SarahG-579462]

Types of changes

This PR allows users to install the optional dependencies found in requirements.txt with pip install POT[all], or specific requirements with pip install POT[backend-pytorch] for example.

Motivation and context / Related issue

This clarifies that requirements.txt are optional dependencies, and finds which modules are optional for specific parts of the code and adds them as an installation option.

The specific install options are: backend-jax, backend-tf, backend-torch, cvxopt, dr, gnn, all.

Using all installs all modules previously available in requirements.txt (which is renamed requirements_opt.txt)

This solves the misunderstanding I had in #622, by clarifying that cvxopt is an optional dependency.

How has this been tested (if it applies)

• running pip install .[subparts] to ensure that the requested modules are installed

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.

[rflamary]

This is nice.

I would like tu name the re quirement file requirements_all.txt instead of
opt. Also It shoudo be used/upadted in the github actions

[rflamary]

Hello @SarahG-579462 ,

Thanks again for your contribution.

We plan on doing a release is a few days. It would be nice to have merged this PR that will allow better installation. Could you have aquicl look at my comment and merge the conflcts with current setup.py?

[rflamary]

thanks @SarahG-579462 , we still need to change the requirement file name to requirements_all.txt and change the file name in all tests and doc build. After that all tests should pass and we can merge

[SarahG-579462]

thanks @SarahG-579462 , we still need to change the requirement file name to requirements_all.txt and change the file name in all tests and doc build. After that all tests should pass and we can merge

Great, thanks for your help !

[codecov]

Codecov Report

Attention: Patch coverage is 71.42857% with 4 lines in your changes missing coverage. Please review.

Project coverage is 96.66%. Comparing base (14c08ba) to head (b8e2629).

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #627      +/-   ##
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- Coverage   96.68%   96.66%   -0.03%     
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  Files          85       85              
  Lines       16890    16898       +8     
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+ Hits        16330    16334       +4     
- Misses        560      564       +4