fix: compatibility with Python 3.14
Dear maintainer, please consider this patch to fix an FTBFS with Python 3.14.
The get_type_hints() function expects a class/function/module object (not an instance). Python 3.14 properly enforces the documented API contract.
This changes all get_type_hints(self) calls to get_type_hints(type(self)) to pass the class instead of the instance.