chore: fix type issue with unenv

Author: pi0

src/adapters/plain.ts

@@ -10,6 +10,7 @@ import {
   setResponseStatus,
   splitCookiesString,
 } from "../utils";
+import { IncomingMessage } from "node:http";
 
 export interface PlainRequest {
   _eventOverrides?: Partial<H3Event>;
@@ -66,7 +67,7 @@ export async function _handlePlainRequest(app: App, request: PlainRequest) {
 
   // Shim for Node.js request and response objects
   // TODO: Remove in next major version
-  const nodeReq = new NodeIncomingMessage();
+  const nodeReq = new NodeIncomingMessage() as unknown /* unenv */ as IncomingMessage;
   const nodeRes = new NodeServerResponse(nodeReq);
 
   // Fill node request properties