#21·Whitelist set storage to correct the pallet version

During pallet-referenda's migration, the storage version was set to pallet version 1. However, since referenda is a newly added pallet for us, we don't require this migration, which has resulted in a mismatch of the pallet version. Submit this proposal to rectify the pallet version discrepancy.

Referenda link: https://darwinia2.subsquare.io/referenda/3.