message: docs(changelog): 2.4.6
diff: # Changelog
  +### [v2.4.6](https://github.com/youzan/vant/compare/v2.4.5...v2.4.6)
  +`2020-02-01`
  +
  +**Bug Fixes**
  +
  +* Picker: should watch columns change [#5614](https://github.com/youzan/vant/issues/5614)
  +
  +
  ### [v2.4.5](https://github.com/youzan/vant/compare/v2.4.4...v2.4.5)
  `2020-02-01`
  