ros-melodic-desktop-full is already the newest version (1.4.1-0bionic.20210719.224425). ...
python-rosdep-modules : Depends: python-rospkg-modules (>= 1.3.0) but it is not going to be installed;
Depends: python-rosdistro-modules (>= 0.7.5) but it is not going to be installed;
ros-melodic-rqt-gui : Depends: python-rospkg-modules but it is not going to be installed;
ros-melodic-rqt-robot-monitor : Depends: python-rospkg-modules but it is not going to be installed；
E: Unmet dependencies. Try 'apt --fix-broken install' with no packages (or specify a solution).