Align GoVulncheck Go version with go.mod

[hogo6002]

GoVulncheck uses local installed GO version to determine vulnerabilities if the env GOVERSION is not defined.
Set the GOVERSION value to the one defined in go.mod.

detail: #679

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 25.00000% with 6 lines in your changes are missing coverage. Please review.

Project coverage is 59.46%. Comparing base (ef3a2a4) to head (f71da79).
Report is 6 commits behind head on main.

Files	Patch %	Lines
internal/sourceanalysis/go.go	25.00%	6 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main     #818       +/-   ##
===========================================
- Coverage   71.79%   59.46%   -12.33%     
===========================================
  Files         118      136       +18     
  Lines        8677    11162     +2485     
===========================================
+ Hits         6230     6638      +408     
- Misses       2078     4099     +2021     
- Partials      369      425       +56     

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[oliverchang]

Is there a test we can add for this?

[another-rex]

Thanks! Added some comments

[another-rex]

LGTM, thanks!