[BD-46] fix: fixed borders for the Dropzone component

[PKulkoRaccoonGang]

Description

• fixed borders for the Dropzone component.

Issue: #2796

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Dropzone component

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (97e23c4) 92.83% compared to head (8191d45) 92.83%.
Report is 1 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #2855   +/-   ##
=======================================
  Coverage   92.83%   92.83%           
=======================================
  Files         235      235           
  Lines        4240     4240           
  Branches     1029     1029           
=======================================
  Hits         3936     3936           
  Misses        300      300           
  Partials        4        4           

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[openedx-semantic-release-bot]

🎉 This PR is included in version 21.7.3 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

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[openedx-semantic-release-bot]

🎉 This PR is included in version 22.0.0-alpha.19 🎉

The release is available on:

• npm package (@alpha dist-tag)
• GitHub release

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