Bump isort from 5.4.2 to 5.5.1 (#2598)

Bumps [isort](https://github.com/pycqa/isort) from 5.4.2 to 5.5.1.
- [Release notes](https://github.com/pycqa/isort/releases)
- [Changelog](https://github.com/PyCQA/isort/blob/develop/CHANGELOG.md)
- [Commits](PyCQA/isort@5.4.2...5.5.1)

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

Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

dev-requirements.txt

@@ -1,7 +1,7 @@
 black==20.8b1
 bravado_core==5.17.0
 flake8==3.8.3
-isort==5.4.2
+isort==5.5.1
 pytest==6.0.1
 pytest-cache==1.0
 pytest-cov==2.10.1