os: linux
dist: xenial
language: python
python:
  - "3.6"
  - "3.7"
install:
  - pip install -r requirements.txt
script:
  - python setup.py test

os: linux
dist: focal
language: python
python:
  - 3.6
  - 3.7
  - 3.8
install:
  - pip install -r requirements.txt
script:
  - python setup.py test

Switch from Ubuntu 16.04 to 20.04 to get Python 3.8
[ci] Switch from Ubuntu 16.04 to 20.04 to get Python 3.8
