- Add back scrollbars that [were hidden when trying to fix another

  bug](https://github.com/wekan/wekan/pull/2132/commits/f7c6b7fce237a6dbdbbd6d728cfb11ad3f4378eb).

Thanks to xet7 !

Closes #2134

client/components/swimlanes/swimlanes.styl

@@ -53,7 +53,6 @@
 .list-group
   flex-direction: row
   height: 100%
-  overflow: hidden
 
 swimlane-color(background, color...)
   background: background !important