fix: ROOT-17: Check conditions for COCO/YOLO Keypoints export

[robot-ci-heartex]

This PR was automatically generated via Follow Merge. Workflow Run Please ensure that all linked upstream Pull Requests are merged before proceeding with this one.

• https://github.com/HumanSignal/label-studio-sdk/pull/467

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 70.75%. Comparing base (ae8179e) to head (327349a). Report is 4 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #405   +/-   ##
=======================================
  Coverage   70.75%   70.75%           
=======================================
  Files          50       50           
  Lines        3030     3030           
=======================================
  Hits         2144     2144           
  Misses        886      886           

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