Only return the latest version for major+minor python versions

[JeanChristopheMorinPerso]

Fixes #82.

Only return the latest version for major+minor python versions instead of returning all versions. Returning all versions is useless in the vast majority of cases.

As a refresher, we need to install python packages for multiple python versions when the package is a python extension (contains compiled code) as explained in https://rez-pip.readthedocs.io/en/latest/faq.html#python-extensions-compiled.

Python extensions don't need to be re-compiled for every single major+minor+patch version of Python.

With this PR, if you have python 3.7.8, 3.7.9, 3.8.1, 3.8.4, 3.8.9 in your repository, running rez-pip numpy will result in numpy being installed for 3.7.9 and 3.8.9 instead of 3.7.8, 3.7.9, 3.8.1, 3.8.4, 3.8.9.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (a08993a) 80.67% compared to head (81e619c) 82.17%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #83      +/-   ##
==========================================
+ Coverage   80.67%   82.17%   +1.50%     
==========================================
  Files           8        8              
  Lines         714      718       +4     
  Branches      126      149      +23     
==========================================
+ Hits          576      590      +14     
+ Misses        120      113       -7     
+ Partials       18       15       -3     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.