Bump black from 19.10b0 to 20.8b1

Bumps [black](https://github.com/psf/black) from 19.10b0 to 20.8b1.
- [Release notes](https://github.com/psf/black/releases)
- [Changelog](https://github.com/psf/black/blob/master/CHANGES.md)
- [Commits](https://github.com/psf/black/commits)

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

poetry.lock

@@ -31,7 +31,7 @@ python = "^3.7"
 django = ">=2.0"
 
 [tool.poetry.dev-dependencies]
-black = "^19.10b0"
+black = "^20.8b1"
 flake8 = "^3.8.3"
 flake8-bandit = "^2.1.2"
 flake8-bugbear = "^20.1.4"