[Update] Package manager를 npm에서 yarn으로 변경하라

[saseungmin]

• Yarn v1 Package manager으로 변경
• Fix broken test

[codecov-commenter]

Codecov Report

Merging #237 (4966798) into main (4a62565) will not change coverage. The diff coverage is n/a.

@@           Coverage Diff           @@
##             main     #237   +/-   ##
=======================================
  Coverage   99.70%   99.70%           
=======================================
  Files         111      111           
  Lines        1351     1351           
  Branches      187      187           
=======================================
  Hits         1347     1347           
  Misses          4        4           

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