Add py.typed marker file (as defined by PEP 561)

[jonemo]

Addresses #45

Adds the py.typed file as per PEP 561. This ensures that projects that import InquirerPy can be type checked.

[kazhala]

LGTM. Thanks for doing this.

[jonemo]

@kazhala Thanks for the quick merge!

Two followups:

1. Can you close Missing py.typed marker file for PEP 561 #45 ? I don't seem to be able to do that myself.
2. Merging my PR into master seems to have broken the pyright step of the CI pipeline in a major way. I am not quite sure how my change could cause these errors, can you take a look?

[kazhala]

Hi @jonemo ,

Thanks again for doing this. I should have touched up in the issue ticket for this. No not your changes broke the pyright lints, think pyright updated some checks around Optional[XXX] which I need to update the codebase to align with that.

I've been quite busy for the last few months and should have fixed the pyright thing first. I'll close your issue once I fix the linting and make a quick release.

Thanks