Please add rs-colors

[ralph-schleicher]

Please add the rs-colors library available from
https://github.com/ralph-schleicher/rs-colors.git

The rs-colors library provides a color data type for Common Lisp.
The home page is https://github.com/ralph-schleicher/rs-colors.

[quicklisp]

Failure log here: http://report.quicklisp.org/2020-02-11/failure-report/rs-colors.html

[ralph-schleicher]

Fixed.