upgrade chart.js 2.7.2 and fix #247

[mizukami234]

• Simply upgraded chart.js to 2.7.2
  • this version contains a stacked group's bugfix Correctly handle stacked groups when not adjacent chartjs/Chart.js#4937
• fixed Mix chart, labels.slice is not a function error #247

[mizukami234]

Hi @jerairrest , could you please merge this?
I need this bugfix: chartjs/Chart.js#4937

[bagratinho]

please @jerairrest take time to merge this as I assume this will also fix #337

[rpearce]

If chart.js is a peerDependency, as shown here https://github.com/jerairrest/react-chartjs-2/blob/master/package.json#L67, then you should be able to specify your own chart.js version in your project, and that will take precedence.

I am not in charge of this project but just came across this PR.

[jerairrest]

I agree with rpeace. Closing since a peer dependency would fix this issue.