Do not allow voters to change vote after voting

[metrox-eth]

Initially started by Coder Dan on Canny
March 23, 2021

After a vote has been cast, it should not be able to be changed. Or at least the Snapshot owner should be able to toggle on/off whether or not votes can be recast for their space.

Comments from Canny:

1. Paul M | Float
   From an implementation standpoint, I imagine this can be done relatively easily with a check in the hub (around L217 of server/index.ts) if that (body.address, msg.payload.proposal) combination is already present, much like the check for an unknown proposal.
   You could update the schema slightly to save proposal id alongside to make the search efficient, but given that there probably aren't that many messages per (address, space) you may not need to.

2. Muhammad Fadjril Lubis
   Good idea since some people could change their mind because there are interferences from other people or even worst, there are some sort of good offers or threats.