Bump chart.js from 2.7.0 to 2.9.4
Bump chart.js from 2.7.0 to 2.9.4

Bumps [chart.js](https://github.com/chartjs/Chart.js) from 2.7.0 to 2.9.4.
- [Release notes](https://github.com/chartjs/Chart.js/releases)
- [Commits](https://github.com/chartjs/Chart.js/compare/v2.7.0...v2.9.4)

Signed-off-by: dependabot[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@github.com>
y-takey/chartjs-plugin-stacked100,y-takey/chartjs-plugin-stacked100