fixup! Remove the (now) unused Config.package_args() method

Author: llucax

src/frequenz/repo/config/nox/config.py

@@ -13,7 +13,6 @@
 """
 
 import dataclasses as _dataclasses
-import itertools as _itertools
 from typing import Self, assert_never, overload
 
 import nox as _nox