Support PyStubType for numpy's PyReadonlyArray

[unkcpz]

The PyStubType for the `PyReadonlyArray was not support, I add it to the numpy.rs and it seems works for my case where the type is PyReadonlyArray.

[zao111222333]

Hi, I want to participate to relf/egobox#237 as well, and here is my suggestion for this PR, we can reuse the PyArray's code as following:

impl<T: NumPyScalar + Element, D: Dimension> PyStubType for PyReadonlyArray<'_, T, D> {
    fn type_output() -> TypeInfo {
        PyArray::<T, D>::type_output()
    }
}