Type check python driver in CI

[krishnangovindraj]

Problem to Solve

Bugs can hide in paths our tests don't exercise.

Current Workaround

None. It has to break for us to notice.

Proposed Solution

Run a static type-check (such as mypy) in CI

Additional Information

Most of our driver is already annotated (likely Dmitrii II ran type-checks when he was working on it). So it's not much work to complete annotations and fix problems.