TG-946 Add truthy-bool rule to pyproject.toml

[niccolomineo]

Adds the pyproject rule implementing the following concept:

Sometimes code uses boolean checks on variables that can only be true. This is normally a sign of a mistake, either in the type hints or the implementation. Mypy has an optional check that can find such problematic boolean usage with its truthy-bool error code.

https://adamj.eu/tech/2022/10/24/python-type-hints-truthy-bool/