Fix Version/s: None
As a pilot for incorporating static type checking to SQuaRE's products, let's add type checking to Documenteer as part of its 0.6 overhaul.
This ticket is to add mypy type checking to Documenteer through the pytest-mypy plugin. The goal is to have tests pass with a minimum of work. Future tickets can incidentally add explicit typing to Documenteer's APIs.
This ticket will be part of documenteer 0.6