fix: shadowed variable causes error

[davepgreene]

This PR fixes an issue where the local ok shadows the global assignment on line 15 which caused this error to always appear in healthchecks:

- ❌ ERROR Failed to run healthcheck for "go" plugin. Exception:
  ...user/.local/share/nvim/lazy/go.nvim/lua/go/health.lua:190: attempt to call local 'ok' (a boolean value)

[ray-x]

thanks!