Recently assert-on-tuple had been introduced in tests [1], let's prevent
this.
[1]: https://github.com/ClickHouse/ClickHouse/pull/56367#discussion_r1437098533
v2: pin flake8 to 4.0.1 (instead of originally 6.1) due to other dependencies, hope that it will find such errors
Signed-off-by: Azat Khuzhin <a.khuzhin@semrush.com>
