message: [changelog] 1.5.4
diff: ## Changelog
  +## [v1.5.4](https://github.com/youzan/vant/tree/v1.5.4)
  +`2019-01-20`
  +
  +**Bug Fixes**
  +
  +- fix missing dependencie @vue/babel-helper-vue-jsx-merge-props [\#2474](https://github.com/youzan/vant/issues/2474)
  +
  +
  ## [v1.5.3](https://github.com/youzan/vant/tree/v1.5.3)
  `2019-01-20`
  