Don't change language environment variable

[fcollonval]

This inverts the logic to by default use the default OS locale to set JupyterLab language (if the associated language pack is installed).

It uses the class API of Python gettext instead of the global API as recommended by the Python documentation.

[codecov-commenter]

Codecov Report

Base: 81.05% // Head: 82.14% // Increases project coverage by +1.09% 🎉

Coverage data is based on head (6aeffd1) compared to base (94823fe).
Patch coverage: 83.87% of modified lines in pull request are covered.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #366      +/-   ##
==========================================
+ Coverage   81.05%   82.14%   +1.09%     
==========================================
  Files          22       22              
  Lines        1752     1742      -10     
  Branches      334      330       -4     
==========================================
+ Hits         1420     1431      +11     
+ Misses        231      213      -18     
+ Partials      101       98       -3     

Impacted Files	Coverage Δ
jupyterlab_server/settings_utils.py	78.70% <40.00%> (+0.19%)	⬆️
jupyterlab_server/translations_handler.py	82.14% <80.00%> (-5.86%)	⬇️
jupyterlab_server/translation_utils.py	89.95% <89.36%> (+8.46%)	⬆️

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[blink1073]

Thanks!

[blink1073]

I'll make a minor release tomorrow.

[fcollonval]

Thanks for fixing the CI and the release @blink1073