chore: add shell flag to prepare script (#2646)

Author: nbbeeken

etc/prepare.js

@@ -1,9 +1,10 @@
 #! /usr/bin/env node
 var cp = require('child_process');
 var fs = require('fs');
+var os = require('os');
 
 if (fs.existsSync('src')) {
-  cp.spawn('npm', ['run', 'build:dts'], { stdio: 'inherit' });
+  cp.spawn('npm', ['run', 'build:dts'], { stdio: 'inherit', shell: os.platform() === 'win32' });
 } else {
   if (!fs.existsSync('lib')) {
     console.warn('MongoDB: No compiled javascript present, the driver is not installed correctly.');