refactor(task): Improve task decorator type inference

[CCXLV]

Now the task function with return types other than None will throw static type errors like this basedpyright error:

Argument of type "() -> int" cannot be assigned to parameter "func" of type "(**P@decorator) -> Coroutine[Any, Any, None]" in function "decorator"

And task functions that have return type hint other than None will throw TypeError:

@fluxqueue.task()  
def test_task() -> int:  # <- TypeError
    pass