Remove flake8 dependency (#1276)

* Bump flake8 from 5.0.4 to 6.0.0

Bumps [flake8](https://github.com/pycqa/flake8) from 5.0.4 to 6.0.0.
- [Release notes](https://github.com/pycqa/flake8/releases)
- [Commits](PyCQA/flake8@5.0.4...6.0.0)

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

Signed-off-by: dependabot[bot] <[email protected]>

* Attempt removing flake8

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Josh Moore <[email protected]>

Author: dependabot[bot]

requirements_dev_optional.txt

@@ -14,7 +14,6 @@ types-setuptools
 pymongo==4.3.3
 # optional test requirements
 coverage
-flake8==5.0.4
 pytest-cov==4.0.0
 pytest-doctestplus==0.12.1
 pytest-timeout==2.1.0