`Unused "type: ignore" comment` in CI linting

[gjoseph92]

I'm commonly seeing a linter error in CI about shuffle extension code when modifying unrelated code:

absolufy-imports.........................................................Passed
isort....................................................................Passed
pyupgrade................................................................Passed
black....................................................................Passed
flake8...................................................................Passed
mypy.....................................................................Failed
- hook id: mypy
- exit code: 1
distributed/shuffle/shuffle_extension.py:534: error: Unused "type: ignore" comment

I can't reproduce the error locally, and when I remove the comment, it then does trigger an actual mypy error.

[jrbourbeau]

I believe this was closed by #6779. @gjoseph92 please re-open if I'm missing something