Bump flake8-docstrings in /{{cookiecutter.app_name}}/requirements

Bumps [flake8-docstrings](https://gitlab.com/pycqa/flake8-docstrings) from 1.4.0 to 1.5.0.
- [Release notes](https://gitlab.com/pycqa/flake8-docstrings/tags)
- [Changelog](https://gitlab.com/pycqa/flake8-docstrings/blob/master/HISTORY.rst)
- [Commits](https://gitlab.com/pycqa/flake8-docstrings/compare/1.4.0...1.5.0)

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

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

@@ -12,7 +12,7 @@ black==19.3b0
 flake8==3.7.8
 flake8-blind-except==0.1.1
 flake8-debugger==3.1.0
-flake8-docstrings==1.4.0
+flake8-docstrings==1.5.0
 flake8-isort==2.7.0
 isort==4.3.21
 pep8-naming==0.8.2