color utils: fix compilation on ubuntu 20.04, 18.04
apparently the commented line fails to compile, colorutils.cpp:91:66: error: no matching function for call to ‘QList::QList(QColor*&, QColor*)’
g++ (Ubuntu 9.3.0-17ubuntu1~20.04) 9.3.0 Qt 5.12.8 KF 5.68.0
@pino Are you comfortable with these changes, in order to be merged ?