Update flake8-bugbear requirement

Updates the requirements on [flake8-bugbear](https://github.com/PyCQA/flake8-bugbear) to permit the latest version.
- [Release notes](https://github.com/PyCQA/flake8-bugbear/releases)
- [Commits](PyCQA/flake8-bugbear@19.3.0...21.9.2)

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

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

setup.py

@@ -26,7 +26,7 @@
     'autopep8 >= 1.4.0, < 1.6.0',
     'darglint == 1.8.0',
     'flake8 >= 3.9.0, < 4.0.0',
-    'flake8-bugbear >= 19.3.0, < 20.0.0',
+    'flake8-bugbear >= 19.3.0, < 22.0.0',
     'flake8-docstrings == 1.6.0',
     'flake8-print >= 3.1.0, < 4.0.0',
     'flake8-rst-docstrings < 1.0.0',