ci: Pin the golangci-lint version to prevent breakage

[kylecarbs]

The main branch broke because golangci-lint released a new version.
This pins it, so hopefully it never happens again!

[codecov]

Codecov Report

Merging #62 (248e860) into main (b964cb0) will decrease coverage by 0.17%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main      #62      +/-   ##
==========================================
- Coverage   71.74%   71.57%   -0.18%     
==========================================
  Files          79       79              
  Lines        2902     2902              
  Branches       49       49              
==========================================
- Hits         2082     2077       -5     
- Misses        644      648       +4     
- Partials      176      177       +1     

Flag	Coverage Δ
unittest-go-macos-latest	67.17% <ø> (-0.35%)	⬇️
unittest-go-ubuntu-latest	70.46% <ø> (-0.09%)	⬇️
unittest-go-windows-latest	67.21% <ø> (-0.05%)	⬇️
unittest-js	73.10% <ø> (ø)

Impacted Files	Coverage Δ
peer/conn.go	74.55% <0.00%> (-1.50%)	⬇️

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