ci: use fixed version of go for linting

[jamestelfer]

The v3 action doesn't attempt to set up go, allowing the version already set to be used. This fixes an issue where the linter throws a pile of issues like:

  Error: undeclared name: `FuzzInputSdtringGenerateRandom` (typecheck)
  Error: undeclared name: `AssertEqual` (typecheck)
  Error: undeclared name: `AssertEqualValues` (typecheck)
  Error: undeclared name: `AssertKindOf` (typecheck)
  Error: undeclared name: `AssertTestFails` (typecheck)

An alternative is to set golangci-lint to target 1.18, but this disables a lot of checks.

[codecov]

Codecov Report

Merging #109 (dfcd021) into main (77ba3a4) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main     #109   +/-   ##
=======================================
  Coverage   88.29%   88.29%           
=======================================
  Files          10       10           
  Lines         658      658           
=======================================
  Hits          581      581           
  Misses         40       40           
  Partials       37       37           

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[MarvinJWendt]

Thanks!