feat: change all type hints to modern syntax

[Boss-1s]

Since pyproject.toml advertises >=3.12 for python version, we can technically change all of the type hints to modern syntax (type | type for unions, type | None for optional, etc.) in v3.

[faretek1]

Is type | None or Optional[type] preferred?

[TheCommCraft]

Good question, I would say that both should be accepted, although I personally prefer Optional[T]

[Boss-1s]

https://typing.python.org/en/latest/reference/best_practices.html#shorthand-syntax