Turn off flake8-bugbear check 038 becuase it gave false positives.

[wxtim]

See PyCQA/flake8-bugbear#451

The following files fail the new flake8-bugbear B038 check:

• The two cases in async_util are probably legitimate exceptions to the rule, parly because they are while loops using the modification to empty an object.
• The one in broadcast_report is also using a while loop, but might not need to: It's not a quick fix though - it's 9 YO code and as far as I can see has no unit tests. IMO needs a suite of unit tests existing behaviour before changing. Not a quick win.
• The one is in network/scan.py and option_parsers.py are the result of the bug.

Check List

• I have read CONTRIBUTING.md and added my name as a Code Contributor.
• Contains logically grouped changes (else tidy your branch by rebase).
• Does not contain off-topic changes (use other PRs for other changes).
• Applied any dependency changes to both setup.cfg (and conda-environment.yml if present).
• If this is a bug fix, PR should be raised against the relevant ?.?.x branch.
• This change doesn't require any public facing docs.
• Create an issue to undo this when:
  • Bugbear have fixed their issue.
  • When we have time to devote to the other three issues.