build(deps-dev): update flake8 requirement from ^4.0.1 to ^6.1.0

Updates the requirements on [flake8](https://github.com/pycqa/flake8) to permit the latest version.
- [Commits](PyCQA/flake8@4.0.1...6.1.0)

---
updated-dependencies:
- dependency-name: flake8
  dependency-type: direct:development
...

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

pyproject.toml

@@ -15,7 +15,7 @@ connection-pool = "^0.0.3"
 [tool.poetry.dev-dependencies]
 black = "^22.1.0"
 coverage = {extras = ["toml"], version = "^6.3.1"}
-flake8 = "^4.0.1"
+flake8 = "^6.1.0"
 flake8-bugbear = "^22.1.11"
 pytest = "^7.0"