Use correct npm bin name depending on the OS

Author: sadick254

script/lib/install-script-dependencies.js

@@ -9,8 +9,9 @@ process.env.ELECTRON_CUSTOM_VERSION = CONFIG.appMetadata.electronVersion;
 
 module.exports = function(ci) {
   console.log('Installing script dependencies');
+  const npmBinName = process.platform === 'win32' ? 'npm.cmd' : 'npm';
   childProcess.execFileSync(
-    'npm',
+    npmBinName,
     ['--loglevel=error', ci ? 'ci' : 'install'],
     { env: process.env, cwd: CONFIG.scriptRootPath }
   );