Update black from 18.9b0 to 19.3b0
@@ -19,7 +19,7 @@ pytest-sugar==0.9.2 # https://github.com/Frozenball/pytest-sugar
# ------------------------------------------------------------------------------
flake8==3.7.5 # https://github.com/PyCQA/flake8
coverage==4.5.2 # https://github.com/nedbat/coveragepy
-black==18.9b0 # https://github.com/ambv/black
+black==19.3b0 # https://github.com/ambv/black
# Django
# ------------------------------------------------------------------------------
