cli/base: Use magenta color for warning messages.
cli/base: Use magenta color for warning messages.

Previously used yellow is barely legible with black-on-white terminal
theme as used by default in various distros. Magenta should be readable
for both black-on-white and white-ob-black.

windelbouwman/ppci-mirror,windelbouwman/ppci-mirror,windelbouwman/ppci-mirror,windelbouwman/ppci-mirror,windelbouwman/ppci-mirror,windelbouwman/ppci-mirror