message: [changelog] 2.1.0-beta.2
diff: # Changelog
  +### [v2.1.0-beta.2](https://github.com/youzan/vant/tree/v2.1.0-beta.2)
  +`2019-07-26`
  +
  +**Improvements**
  +
  +- GoodsAction: update style [\#3967](https://github.com/youzan/vant/pull/3967)
  +- ImagePreview: add swipe-duration prop [\#3963](https://github.com/youzan/vant/pull/3963)
  +
  +**Bug Fixes**
  +
  +- fix Sku incorrect button border radius [\#3966](https://github.com/youzan/vant/pull/3966)
  +- fix Tabs incorrect line position in some cases [\#3961](https://github.com/youzan/vant/pull/3961)
  +- fix ImagePreview should reset onClose & onChange option [\#3960](https://github.com/youzan/vant/pull/3960)
  +- fix DatetimePicker incorrect confirm param when use formatter [\#3969](https://github.com/youzan/vant/pull/3969)
  +
  +
  ### [v2.1.0-beta.1](https://github.com/youzan/vant/tree/v2.1.0-beta.1)
  `2019-07-25`
  