Running on NodeJS

While running this plugin on NodeJS we are getting this error (running ChartJS via my [lib](https://github.com/SeanSobey/ChartjsNodeCanvas)):
```
(node:8700) UnhandledPromiseRejectionWarning: ReferenceError: window is not defined
at afterBuildTicks (/home/../node_modules/chartjs-chart-financial/dist/chartjs-chart-financial.min.js:11:2437)
at callback (/home/../node_modules/chart.js/dist/chart.js:800:15)
at TimeSeriesScale._callHooks (/home/../node_modules/chart.js/dist/chart.js:5099:5)
at TimeSeriesScale.afterBuildTicks (/home/../node_modules/chart.js/dist/chart.js:5115:10)
at TimeSeriesScale.update (/home/../node_modules/chart.js/dist/chart.js:5037:10)
...
```
Obviously, the error is from the `window` reference. It looks to just be the one reference, when checking for Luxon, and it can be resolved via something like this:
```
afterBuildTicks: scale => {
if (!('window' in this)) {
return;
}
const DateTime = window && window.luxon && window.luxon.DateTime;
if (!DateTime) {
return;
}
...
```
I am happy to test and submit this via pull request but am just inquiring about interest and appetite to support NodeJS with this fix and going forward?