Fix is None pre-commit check

src/caustics/models/utils.py

@@ -150,7 +150,7 @@ def _init_kwargs_field_check(cls, v, info: ValidationInfo):
             field_name = info.field_name
             field = cls.model_fields[field_name]
             anno_args = typing.get_args(field.annotation)
-            if len(anno_args) == 2 and anno_args[1] == type(None):
+            if len(anno_args) == 2 and anno_args[1] is None:
                 # This means that the anno is optional
                 expected_type = next(
                     filter(lambda x: x is not None, typing.get_args(field.annotation))