Update version to v7.12.0

[kkdai]

Update version to v7.12.0 for Support Messaging API Update 2021/November, Go 1.17 and bug fix.

[codecov-commenter]

Codecov Report

Merging #299 (f928e35) into master (c1241cb) will not change coverage.
The diff coverage is n/a.

❗ Current head f928e35 differs from pull request most recent head 8717271. Consider uploading reports for the commit 8717271 to get more accurate results

@@           Coverage Diff           @@
##           master     #299   +/-   ##
=======================================
  Coverage   78.50%   78.50%           
=======================================
  Files          37       37           
  Lines        2870     2870           
=======================================
  Hits         2253     2253           
  Misses        486      486           
  Partials      131      131           

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