I installed Python 2.7.15rci and Python 3.6.7 on Ubuntu. When i did \'pip list\' on virtualenv it returns me:
Django (2.1.5) pip (9.0.1) pkg-resources (0.0.0
I'm using the python3.8. Similarly to david's answer, use the following command then it works.
$ sudo apt-get install python3.8-dev