VictoryGroup color propType to support function

[Olliebaba]

I am building a chart which has multiple lines, scatter dots for each data point and a tooltip hover over for every scatter dot. I encountered 'z-indexing' issues where the tooltips were hidden behind other descendant siblings following the example in the gallery. (Change second data point of first Victory group to {x: 2, y: 0.5} then hover to see the overlap.) So I tried combining the data and making a single scatter group. The color prop on Victory group is applied to each scatter dot so I realized I could pass a function to dynamically set the color in the same way as VictoryScatter can take a function for size. This works perfectly but throws a propType error, that color must be a string. Can this prop's propTypes be switched to oneOf([string, func])?

[boygirl]

@Olliebaba sorry for the delay. I will make this change in an upcoming version :)