fix: 修复post未能正确处理中间件的问题

src/utils/post.js

@@ -31,7 +31,7 @@ export default async function post(url, data, params = {}, options = {}, auth =
   }
   realOptions.headers['Content-Type'] = 'application/json';
   realOptions.method = 'POST';
-  realOptions.body = JSON.stringify(data);
+  realOptions.body = JSON.stringify(res ? res.data : data);
   return fetch(realUrl, realOptions)
     .then(checkStatus)
     .then(resp => parseObject(resp, middleware.post.onResponse));