fix(renovate): constrain go to 1.21 and do not update golang

[omercnet]

follow up on #833 (comment)

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[another-rex]

Thanks!

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 62.01%. Comparing base (1d6a38d) to head (adf23fe).
Report is 5 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #874      +/-   ##
==========================================
- Coverage   62.16%   62.01%   -0.15%     
==========================================
  Files         144      144              
  Lines       11808    11817       +9     
==========================================
- Hits         7340     7328      -12     
- Misses       3997     4018      +21     
  Partials      471      471              

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