Interface MemberUnmuteEvent

群成员被取消禁言事件（该成员不可能是Bot，见 BotUnmuteEvent）

interface MemberUnmuteEvent {
    member: Member;
    operator: null | Member;
    reply?: ((msgChain: string | MessageChain, quote?: boolean) => Promise<void>);
    type: "MemberUnmuteEvent";
}