Update Route.php

新增路由模块中支持'OPTIONS'类型，该类型为跨域请求api时，ajax自动发送OPTIONS类型的请求报500错误问题

library/think/Route.php

@@ -20,6 +20,7 @@ class Route
         'PUT'    => [],
         'DELETE' => [],
         'HEAD'   => [],
+        'OPTIONS'=> [],
         '*'      => [],
     ];