"no files in package" error

I am trying to build a Python package that wraps the Helm Go SDK, but when I follow the example I get "no files in package" when I try to build:

```sh
$ go mod init github.com/stackhpc/pyhelm3
$ go get helm.sh/helm/v3
$ gopy build helm.sh/helm/v3
no required module provides package helm.sh/helm/v3; to add it:
go get helm.sh/helm/v3
2022/08/18 10:11:58 Note: there was an error building [helm.sh/helm/v3] -- will continue but it may fail later: exit status 1
gopy: no files in package "helm.sh/helm/v3"
2022/08/18 10:11:58 error dispatching command: gopy: no files in package "helm.sh/helm/v3"
```

What am I missing? Any help would be greatly appreciated.