Bump flake8-bugbear from 21.4.3 to 21.9.1 (#623)

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] <[email protected]>

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

requirements-dev.txt

@@ -1,7 +1,7 @@
 attrs==21.2.0
 flake8==3.9.2
 flake8-bandit==2.1.2
-flake8-bugbear==21.4.3
+flake8-bugbear==21.9.1
 flake8-import-order==0.18.1
 flake8-requirements==1.5.1
 sphinx==4.1.2