Bump xchart from 3.6.6 to 3.7.0
Bump xchart from 3.6.6 to 3.7.0

Bumps [xchart](https://github.com/knowm/XChart) from 3.6.6 to 3.7.0.
- [Release notes](https://github.com/knowm/XChart/releases)
- [Commits](https://github.com/knowm/XChart/compare/xchart-3.6.6...xchart-3.7.0)

Signed-off-by: dependabot-preview[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@dependabot.com>
timmolter/XChange,douggie/XChange,stachon/XChange,andre77/XChange