Could not find a version that satisfies the requirement in python

Run this command and try again

curl https://bootstrap.pypa.io/get-pip.py | python

The detailed description can be found in the link shared by Anupam in the comments.

If you are using python 3.x, Please try this commands

sudo pip3 install --upgrade pip

sudo pip3 install virtualenv

Please try below commands

pip install --upgrade virtualenv

We tried the above but they didn't work in our case because we had two versions of python3 on the systems. One via a normal install a few months back and one via brew (on a Mac). When we discovered that, we downloaded and installed the latest version from python.org and as a result the pip was updated too. Once the pip was installed the sudo pip3 install virturaenv command worked fine.