GetChatPinnedStories constructor
Returns the list of pinned stories posted by the given chat. The stories are returned in a reverse chronological order (i.e., in order of decreasing story_id).. For optimal performance, the number of returned stories is chosen by TDLib
Implementation
const GetChatPinnedStories({
  required this.chatId,
  required this.fromStoryId,
  required this.limit,
});