update to ESModules

Author: glasnt

appengine/metadata/standard/package.json

@@ -9,6 +9,7 @@
     "type": "git",
     "url": "https://github.com/GoogleCloudPlatform/nodejs-docs-samples.git"
   },
+  "type": "module",
   "engines": {
     "node": "20.x"
   },

appengine/metadata/standard/server.js

@@ -14,8 +14,8 @@
 
 'use strict';
 
-const express = require('express');
-const fetch = require('node-fetch');
+import express from 'express';
+import fetch from 'node-fetch';
 
 const app = express();
 app.enable('trust proxy');
@@ -57,4 +57,5 @@ app.listen(PORT, () => {
   console.log(`App listening on port ${PORT}`);
   console.log('Press Ctrl+C to quit.');
 });
-module.exports = app;
+
+export default app;

appengine/metadata/standard/test/server.test.js

@@ -1,6 +1,5 @@
-const path = require('path');
-const supertest = require('supertest');
-const app = require(path.join(__dirname, '../', 'server.js'));
+import supertest from 'supertest';
+import app from '../server.js';
 
 it('should be listening', async () => {
   await supertest(app).get('/').expect(200);