We should have a look at upgrading pip, since the new resolver got in. It might solve quite a few issues:
https://pip.pypa.io/en/latest/user_guide/#changes-to-the-pip-dependency-resolver-in-20-2-2020
Since catkin is ROS1 focused, the main (and only?) target is now http://wiki.ros.org/noetic which means Python3, finally. http://wiki.ros.org/noetic/Migration
We should have a look at upgrading pip, since the new resolver got in. It might solve quite a few issues:
https://pip.pypa.io/en/latest/user_guide/#changes-to-the-pip-dependency-resolver-in-20-2-2020
Since catkin is ROS1 focused, the main (and only?) target is now http://wiki.ros.org/noetic which means Python3, finally. http://wiki.ros.org/noetic/Migration