fix import statement

Author: Calvinn Ng

core/util/messenger.ts

@@ -1,5 +1,5 @@
 import { v4 as uuidv4 } from "uuid";
-import type { IProtocol } from "../protocol";
+import type { IProtocol } from "../protocol/index.js";
 
 export interface Message<T = any> {
   messageType: string;