Bump black in /{{cookiecutter.app_name}}/requirements

Bumps [black](https://github.com/psf/black) from 19.3b0 to 19.10b0.
- [Release notes](https://github.com/psf/black/releases)
- [Commits](https://github.com/psf/black/commits)

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

{{cookiecutter.app_name}}/requirements/dev.txt

@@ -8,7 +8,7 @@ factory-boy==2.12.0
 pdbpp==0.10.2
 
 # Lint and code style
-black==19.3b0
+black==19.10b0
 flake8==3.7.9
 flake8-blind-except==0.1.1
 flake8-debugger==3.2.1