machine:
  python:
    version: 3.6.1
database:
  pre:
    - python manage.py makemigrations
    - python manage.py migrate
test:
  override:
    - coverage run manage.py test
  post:
    - coverage html -d $CIRCLE_ARTIFACTS

machine:
  python:
    version: 3.6
database:
  pre:
    - python manage.py makemigrations
    - python manage.py migrate
test:
  override:
    - coverage run manage.py test
  post:
    - coverage html -d $CIRCLE_ARTIFACTS

Change the python version to 3.6
Change the python version to 3.6
