v5.28.0

changes from v5.27.0

docs

• addition of the serpentine timeline example (via #3858). (Thanks @Giammaria!)
• update to the zoomable circle packing example (via #3857). (Thanks @Giammaria and @domoritz!)
• update vega datasets (via #3863). (Thanks @domoritz!)

vega-parser

• allow signals in scale nice (via #3887). (Thanks @lsh!)

vega-scenegraph

• convert some of the scenegraph types to classes (via #3864). (Thanks @lsh!)

vega-typings

• add missing aggregate_params to window transform type (#3874). (Thanks @julieg18!)
• bump typings to 1.2 (Thanks @domoritz!)