Chart.js 3.0 support

[benmccann]

Chart.js 3.0 is out now, so it might be nice for this plugin to upgrade to it

[alexbakker]

Is anyone currently working on this? If not, I might give it a shot.

[samber]

@alexbakker sure!

https://www.chartjs.org/docs/latest/getting-started/v3-migration.html

Looks like the support of momentjs has changed.

Data model of axes and scales are a bit different.

Metadata API has changed, but I'm pretty sure we are not concerned about that.

In case you have a better understanding of the work for the update. Feel free to share a simple todo-list. ;)

[samber]

Closing as we upgraded to chartjs 4