Remove hard-coded module path

[kylebarron]

When we upgrade to pyo3 0.23 we should be able to remove the module from the definition of PyArray, which means that we should be able to let end users choose the name of the module on their export.

#[pymodule]
#[pyo3(module = "arro3.core")]
mod my_extension {
    #[pymodule_export]
    use pyo3_arrow::PyArray;
}

[kylebarron]

I don't think this is possible to solve currently. We export separate APIs for users to create PyCapsule objects, so I don't think this is necessary to solve anymore.