New review comment by ericonr on void-packages repository

https://github.com/void-linux/void-packages/pull/30634#discussion_r625427360

Comment:
```suggestion
go_import_path="github.com/golang-migrate/migrate/v4"
go_package="cmd/migrate"
```

I think. Even if the value isn't being used anyway :p

Can probably omit `go_package`.