feat(node): only support v14 and v16
feat(node): only support v14 and v16

BREAKING CHANGE: Only supporting Node v14 and v16 now

Signed-off-by: Will Soto <d409ca4f0aac9df35db43d4cd46d459d839678fe@users.noreply.github.com>

willsoto/ng-chartist,willsoto/ng-chartist,willsoto/ng-chartist