-r requirements.txt

pytest==4.2.0
pytest-cov==2.6.1
pytest-mock==1.10.1
codecov==2.0.15
coverage==4.5.2
flake8==3.7.5
black==18.9b0

-r requirements.txt

pytest==4.2.0
pytest-cov==2.6.1
pytest-mock==1.10.1
codecov==2.0.15
coverage==4.5.2
flake8==3.7.5
black==19.3b0

Update black from 18.9b0 to 19.3b0
Update black from 18.9b0 to 19.3b0