Allow installation on all platform

[doctolivier]

Fixe #64

On my Electron app, I need to supporte multiple OS and I would like to use your package to enhance the mac permissions experience, but I can't add it easely because of the npm os limitation. It failing my npm installation on local and CI although I've added the package in optionalDependency.

This is why I propose this changes that allow installation and usage on all platform but the APIs will return undefined if not macOs.

[doctolivier]

@codebytere If you can take a look or if it's not planned to support others OS 👍