chore(dependencies): update dependency isort to ^5.9.3

Author: renovate-bot

pyproject.toml

@@ -30,7 +30,7 @@ python = "^3.6"
 [tool.poetry.dev-dependencies]
 black = "^20.8b1"
 coverage = "^5.3.1"
-isort = "^5.8.0"
+isort = "^5.9.3"
 tox = "^3.24.3"
 tox-gh-actions = "^2.6.0"