Fix nested-classes-whitelist default value (#1093) (#1094)

CHANGELOG.md

@@ -10,6 +10,7 @@ We used to have incremental versioning before `0.1.0`.
 
 - Fixes supported python versions in PyPI to be `3.6` and `3.7`
 - Fix false positive ImplicitYieldFromViolation for async functions #1057
+- Fixes nested-classes-whitelist option default value for flake8 prior 3.7.8 #1093
 
 ### Misc
 

wemake_python_styleguide/options/config.py

@@ -129,15 +129,15 @@
 
 """
 
-from typing import ClassVar, FrozenSet, Mapping, Optional, Sequence, Union
+from typing import ClassVar, Mapping, Optional, Sequence, Union
 
 import attr
 from flake8.options.manager import OptionManager
 from typing_extensions import final
 
 from wemake_python_styleguide.options import defaults
 
-ConfigValuesTypes = Union[str, int, bool, FrozenSet[str]]
+ConfigValuesTypes = Union[str, int, bool, Sequence[str]]
 
 
 @final

wemake_python_styleguide/options/defaults.py

@@ -33,10 +33,10 @@
 MAX_NOQA_COMMENTS: Final = 10  # guessed
 
 #: List of nested classes' names we allow to use.
-NESTED_CLASSES_WHITELIST: Final = frozenset((
+NESTED_CLASSES_WHITELIST: Final = (
     'Meta',  # django forms, models, drf, etc
     'Params',  # factoryboy specific
-))
+)
 
 
 # ===========