Add delete_roles action to remove a role from a group

[KYash03]

Resolves #14158

[nijel]

Can you please:

• Add tests for this new endpoint?
• Add documentation for this (mention in the changes.rst and add to api.rst).

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 91.02%. Comparing base (561b199) to head (9a2bb10).
Report is 3185 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #14226      +/-   ##
==========================================
+ Coverage   91.01%   91.02%   +0.01%     
==========================================
  Files         610      610              
  Lines       63926    63945      +19     
  Branches     6615     6615              
==========================================
+ Hits        58181    58205      +24     
+ Misses       4035     4030       -5     
  Partials     1710     1710              

Files with missing lines	Coverage Δ
weblate/api/tests.py	100.00% <100.00%> (ø)
weblate/api/views.py	89.45% <100.00%> (+0.08%)	⬆️

... and 2 files with indirect coverage changes

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[nijel]

Merged, thanks for your contribution!