Set prettier external deps

Rokt33r · Rokt33r · commit d1fd5cfb458f · 2019-10-10T18:01:09.000+09:00
diff --git a/webpack-skeleton.js b/webpack-skeleton.js
@@ -30,6 +30,7 @@ var config = {
     ]
   },
   externals: [
+    'prettier',
     'node-ipc',
     'electron',
     'lodash',
