support `package.json5` + `package.yaml` for pnpm

[danielroe]

Describe the feature

In addition to the traditional package.json format, pnpm also supports package.json5 (via json5) and package.yaml (via js-yaml).

https://pnpm.io/package_json

Additional information

• Would you be willing to help implement this feature?

[pi0]

Fortunatly we have confbox as a dep it is easy to add!