• I have added a news fragment under changelog.d/ (if the patch affects the end users)

Summary of changes

Apply ruff rule RUF012

RUF012 Mutable class attributes should be annotated with `typing.ClassVar`

Gitr rid of mutable default values:

• list → tuple
• list → field(default_factory=list) (using dataclass instead of NamedTuple)
• dict → field(default_factory=dict)(using dataclass instead of NamedTuple)

Fixes #1408.

Test plan

Tested by running

$ ruff check --extend-select RUF012
All checks passed!
$