Bump version to 1.2.0

[ChoiByungWook]

Issue #, if available:

Description of changes:

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• I have read the CONTRIBUTING doc
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[codecov-io]

Codecov Report

❗ No coverage uploaded for pull request base (master@fa61b11). Click here to learn what that means.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master      #73   +/-   ##
=========================================
  Coverage          ?   92.23%           
=========================================
  Files             ?       52           
  Lines             ?     3115           
  Branches          ?       82           
=========================================
  Hits              ?     2873           
  Misses            ?      242           
  Partials          ?        0

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