Support taking the `.tgz` as input

Would be nice to be able to do something like

```bash
pnpx pkg-pr-new publish './artfiacts/*.tgz'
```

We have a repo which has a specific way of deciding what to build and just doing `packages/*` breaks. While I can resolve the list and pass it explicitly it would be nice to just be able to rely on existing step that compute what packages to build and pack them.