Add color as hex works

[jcastroa87]

This PR fix the issue about Yellow color in our demo Chart

Issue: https://github.com/Laravel-Backpack/PRO/pull/195

[pxpm]

Thanks @jorgetwgroup can confirm it works with hex color.

They are the same color, but hey 🤷 nice catch!

[welcome[bot]]

WHOOP-WHOOP! Congrats, your first PR on this repo has officialy been merged.

If you want to help out the community in other ways, you can:

• give your opinion on other Github Issues & PRs;
• chat with others in the Gitter Chatroom (usually for quick help: How do I do X);
• answer Backpack questions on Stackoverflow; you get points, people get help; you can subscribe to the backpack-for-laravel tag by adding a new filter; that will send you emails when new questions come up with our tag;

Again. Thank you for the PR. You are a wonderful person. Keep 'em coming :-) Cheers!

-- Justin Case The Backpack Robot

P.S. Help in the Backpack community is rewarded with free Backpack commercial licenses. It's the least we can do. If you feel you've helped the community with PRs, help & other stuff, please shoot Tabacitu an email and ask him if you qualify for free licenses. You scratch my back, I scratch your back. Thank you!