This change uses typing.get_type_hints instead of inspect.signature since the former will try to eval string type hints (PEP-563) and will return an object rather than a string if it was successful which will allow the remaining code to work. inspect.signature on the other hand does not have the ability to resolve string type hints until Python 3.10 and has to be called with eval_str=True

This also partially reverts #428, but fixes #426 correctly by not failing on the isclass(hint_class) check due to annotations not "really" being classes.

This latter change is done because list[str] is unconditionally and improperly unwrapped and will result in a type of str since list's annotations will also have a first argument of str.