fix: can't sign in by cookie on leetcode-cn site (#55)

* fix: can't sign in by cookie on leetcode-cn site

* Used const instead of let

Author: dzz007

Diff for: lib/plugins/leetcode.js

@@ -534,15 +534,9 @@ plugin.login = function(user, cb) {
 };
 
 function parseCookie(cookie, body, cb) {
-  const isCN = config.app === 'leetcode.cn';
   const SessionPattern = /LEETCODE_SESSION=(.+?)(;|$)/;
-  let csrfPattern;
-  if (isCN) {
-    csrfPattern = /name="csrfmiddlewaretoken" value="(.*?)"/;
-  } else {
-    csrfPattern = /csrftoken=(.+?)(;|$)/;
-  }
-  const reCsrfResult = csrfPattern.exec(isCN? body: cookie);
+  const csrfPattern = /csrftoken=(.+?)(;|$)/;
+  const reCsrfResult = csrfPattern.exec(cookie);
   const reSessionResult = SessionPattern.exec(cookie);
   if (reSessionResult === null || reCsrfResult === null) {
     return cb('invalid cookie?');