message: [changelog] 1.5.5
diff: ## Changelog
  +## [v1.5.5](https://github.com/youzan/vant/tree/v1.5.5)
  +`2019-01-21`
  +
  +**Bug Fixes**
  +
  +- fix Field type prop not work [\#2579](https://github.com/youzan/vant/pull/2579)
  +
  +
  ## [v1.5.4](https://github.com/youzan/vant/tree/v1.5.4)
  `2019-01-20`
  