fix: remove is-windows test fixture code from module

Author: wraithgar

lib/is-server-package.js

@@ -1,7 +1,6 @@
-const util = require('util')
-const fs = require('fs')
-const { stat } = fs.promises || { stat: util.promisify(fs.stat) }
-const { resolve } = require('path')
+const { stat } = require('node:fs/promises')
+const { resolve } = require('node:path')
+
 module.exports = async path => {
   try {
     const st = await stat(resolve(path, 'server.js'))