Bump flake8 from 3.8.1 to 3.8.2

Bumps [flake8](https://gitlab.com/pycqa/flake8) from 3.8.1 to 3.8.2.
- [Release notes](https://gitlab.com/pycqa/flake8/tags)
- [Commits](https://gitlab.com/pycqa/flake8/compare/3.8.1...3.8.2)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

requirements-tests.txt

@@ -3,5 +3,5 @@ attrs==19.3.0
 pytest==5.4.2
 pytest-cov==2.8.1
 mock==2.0.0
-flake8==3.8.1
+flake8==3.8.2
 pyflakes==2.2.0