build(deps-dev): bump black from 21.4b0 to 21.4b2

Bumps [black](https://github.com/psf/black) from 21.4b0 to 21.4b2.
- [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>

setup.py

@@ -69,7 +69,7 @@ setuptools.setup(
             "pytest-instafail==0.4.2",
             "pytest-cov==2.11.1",
             "pycodestyle==2.7.0",
-            "black==21.4b0",
+            "black==21.4b2",
             "isort==5.8.0",
         ]
     },