Modernize GitHub Actions workflow for current Go toolchain.

[BrandonStalnaker]

Background

• CI was outdated and failing

What Has Changed

• Replace archived golint (broken under Go 1.18+) with go vet and advisory staticcheck/gofmt checks so CI can build again.

Checklist

• I have performed a self-review of my own code.
• I have made corresponding changes to the documentation.
• I have added tests that prove my fix is effective or that my feature works.
• I have tested this locally.

Additional Notes

• {Any additional information or context relevant to this PR}

Reference Issue (For employees only. Ignore if you are an outside contributor)

• Closes https://go/j/[ticket-number]

[cursor]

PR Summary

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