An issue has been identified in the Moonriver & Moonbeam runtimes that is also present in RT4301.  This proposal is to cancel the authorization of the upgrade to runtime 4301 on Moonbeam.

Please see the [forum post](https://forum.moonbeam.network/t/mb152-cancel-moonbeam-referendum-150-upgrade-to-rt4301/2476) for more details.

Cancel an ongoing referendum.

- `origin`: must be the `CancelOrigin`.
- `index`: The index of the referendum to be cancelled.

Emits `Cancelled`.

#152 [MB152] Cancel Moonbeam Referendum 150 (Upgrade to RT4301)