Fix swagger specification

[Marishka17]

Motivation and context

Resolved #6823

How has this been tested?

Checklist

• I submit my changes into the develop branch
• I have added a description of my changes into the CHANGELOG file
• I have updated the documentation accordingly
• I have added tests to cover my changes
• I have linked related issues (see GitHub docs)
• I have increased versions of npm packages if it is necessary
  (cvat-canvas,
  cvat-core,
  cvat-data and
  cvat-ui)

License

• I submit my code changes under the same MIT License that covers the project.
  Feel free to contact the maintainers if that's a concern.

[codecov]

Codecov Report

Merging #6825 (ce5439e) into develop (6826dda) will increase coverage by 0.00%.
The diff coverage is n/a.

@@           Coverage Diff            @@
##           develop    #6825   +/-   ##
========================================
  Coverage    82.47%   82.48%           
========================================
  Files          369      369           
  Lines        39790    39790           
  Branches      3547     3547           
========================================
+ Hits         32817    32819    +2     
+ Misses        6973     6971    -2     

Components	Coverage Δ
cvat-ui	77.47% <ø> (+<0.01%)	⬆️
cvat-server	86.87% <ø> (+<0.01%)	⬆️

[nmanovic]

LGTM