Type hints?

[woodruffw]

pip-audit is consuming pip-api, and is aiming for 100% MyPy coverage in the process.

pip-api currently doesn't have any type signatures, so we disable our MyPy checking wherever we import pip_api.

Is adding type signatures to the public APIs worth it here? If so, it's something we could dedicate engineering time to.

[di]

I think the public API here is simple enough that this shouldn't be hard to do, and would be beneficial for pip-audit. So yes, I think it's worth doing!