[scale] bump d3-scale dep for scaleSymlog

[hshoff]

Counterpart to #470 which makes sure the correct d3-scale version is installed to support the addition of scaleSymlog.

💥 Breaking changes

• [scale] d3-scale 2.2.2 changed the behavior of a collapsed domain. See this comment for how to handle the updated behavior.

🚀 Enhancements

• [scale] bump d3-scale dep to ^2.2.2 for scaleSymlog

Sidenote: Since d3-scale added convenience constructors (scale(domain, range)) we may deprecate @vx/scale in favor of d3-scale in the future. Currently, @vx/scale only adds two additional behaviors around d3-scale: Convenience constructors (as named args: scale({ domain, range })) and a .type property on scale instances. These benefits may not be worth the cost of maintaining the wrapping functions. I always thought i would add a way to make scales immutable, but it may not be worth it anymore.