Bump isort from 4.3.19 to 4.3.20 in /{{cookiecutter.app_name}}

Bumps [isort](https://github.com/timothycrosley/isort) from 4.3.19 to 4.3.20.
- [Release notes](https://github.com/timothycrosley/isort/releases)
- [Changelog](https://github.com/timothycrosley/isort/blob/4.3.20/CHANGELOG.md)
- [Commits](https://github.com/timothycrosley/isort/compare/4.3.19...4.3.20)

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

{{cookiecutter.app_name}}/Pipfile

@@ -56,5 +56,5 @@ flake8-debugger = "==3.1.0"
 flake8-docstrings = "==1.3.0"
 flake8-isort = "==2.7.0"
 flake8-quotes = "==2.0.1"
-isort = "==4.3.19"
+isort = "==4.3.20"
 pep8-naming = "==0.8.2"