The payload of :thread_members_update: users were added to or removed
from a thread. id is the thread's; member_count stops at 50.
Summary
Types
@type t() :: %Lingo.Event.ThreadMembersUpdate{ added_members: [Lingo.Type.ThreadMember.t()], guild_id: String.t(), id: String.t(), member_count: non_neg_integer(), removed_member_ids: [String.t()] }