fix e2e (#609)

Author: conico974

examples/app-router/app/api/sse/route.ts

@@ -1,6 +1,11 @@
-import { wait } from "@open-next/utils";
 import type { NextRequest } from "next/server";
 
+function wait(ms: number) {
+  return new Promise((resolve) => {
+    setTimeout(resolve, ms);
+  });
+}
+
 export const dynamic = "force-dynamic";
 
 export async function GET(request: NextRequest) {