Bump flake8-bugbear from 21.4.3 to 21.9.1

Bumps [flake8-bugbear](https://github.com/PyCQA/flake8-bugbear) from 21.4.3 to 21.9.1.
- [Release notes](https://github.com/PyCQA/flake8-bugbear/releases)
- [Commits](PyCQA/flake8-bugbear@21.4.3...21.9.1)

---
updated-dependencies:
- dependency-name: flake8-bugbear
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

setup.py

@@ -5,7 +5,7 @@
     "marshmallow": ["marshmallow>=3.13.0"],
     "yaml": ["PyYAML>=3.10"],
     "validation": ["prance[osv]>=0.11"],
-    "lint": ["flake8==3.9.2", "flake8-bugbear==21.4.3", "pre-commit~=2.4"],
+    "lint": ["flake8==3.9.2", "flake8-bugbear==21.9.1", "pre-commit~=2.4"],
     "docs": [
         "marshmallow>=3.13.0",
         "pyyaml==5.4.1",