import { Api } from "https://dotland.deno.dev/x/grammy@v1.15.0/mod.ts";
Use this method to set the thumbnail of a custom emoji sticker set. Returns True on success.
Parameters
Custom emoji identifier of a sticker from the sticker set; pass an empty string to drop the thumbnail and use the first sticker as the thumbnail.
Optional AbortSignal to cancel the request
Official reference: https://core.telegram.org/bots/api#setcustomemojistickersetthumbnail