deps: update dependency com.google.protobuf:protobuf-java to v3.12.2

[renovate-bot]

This PR contains the following updates:

Package	Update	Change
com.google.protobuf:protobuf-java	patch	3.12.0 -> 3.12.2

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[codecov]

Codecov Report

Merging #138 into master will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master     #138   +/-   ##
=========================================
  Coverage     61.34%   61.34%           
  Complexity       29       29           
=========================================
  Files             6        6           
  Lines           194      194           
  Branches          2        2           
=========================================
  Hits            119      119           
  Misses           73       73           
  Partials          2        2           

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