dev: Enchance development environment setup with `pythonista-stubs` package

[o-murphy]

We can add pythonista-stubs as dev dependency to the project to have type hints for the Pythonista built-in modules as console, ui, keychain etc. I was contributed there and I can say that is very helpfull

[o-murphy]

@omz

I'm not sure it is directly related to Pythonista itself. The Pythonista can't use this stubs anyway, it's more likely for stash maintenance or other packages that uses Pythonista built-in API, like bleak-pythonista.