I gave up on the virtual environment. no combination worked, even the same combination as the one provided in the documentation fails.
I upgraded to Ubuntu 20.04 LTS and use the latest python3 libraries. The DroneKit Software is to say it politely, in need of upgrading. And to be honest the entire video and documentation provided in these courses is so far behind, it made thing more difficult to implement, that if I just did it on my own. I literally invested hours on these for very little gains.