An event handler for a vote in a poll. This event is only triggered when the bot is the author of the poll, and the vote is made by another actor. If the poll allows multiple selections, this event is triggered multiple times, once for each option selected by the actor.
Note that this event can be triggered even if the voter vote an option multiple times or multiple options for a poll that disallows multiple selections. You should validate the vote in the event handler by storing the votes in a persistent store, and checking if the vote is valid. (This behavior can subject to change in the future.)
VoteEventHandler<TContextData>