fix default parameter for `palette` with `ly_image`
fix default parameter for `palette` with `ly_image`

paultcochrane/rbokeh,jrounds/rbokeh,timelyportfolio/rBokeh,sinhrks/rbokeh,paultcochrane/rbokeh,sinhrks/rbokeh,timelyportfolio/rBokeh,jrounds/rbokeh