Python 3.7 on Ubuntu 20.04
Do you need Ubuntu 20.04? Ubuntu 18.04 comes with Python 3.6, and 3.7 available.
If you do, the deadsnakes PPA has Python 3.5-3.7 for Ubuntu 20.04 (Focal). To add it and install:
sudo add-apt-repository ppa:deadsnakes/ppasudo apt-get updatesudo apt-get install python3.7P.s. I'm not a dev and have no experience with Tensorflow so take this with a grain of salt.