remove choicefieldmixin check - should be unnecessary

Author: bckohan

src/django_enum/fields.py

@@ -676,7 +676,7 @@ def formfield(self, form_class=None, choices_form_class=None, **kwargs):
         #   we try to pass in. Very annoying because we have to
         #   un-encapsulate some of this initialization logic, this makes our
         #   EnumChoiceField pretty ugly!
-        from django_enum.forms import ChoiceFieldMixin, EnumChoiceField, NonStrictSelect
+        from django_enum.forms import EnumChoiceField, NonStrictSelect
 
         if not self.strict:
             kwargs.setdefault("widget", NonStrictSelect)
@@ -687,12 +687,9 @@ def formfield(self, form_class=None, choices_form_class=None, **kwargs):
             **kwargs,
         )
 
-        if isinstance(form_field, ChoiceFieldMixin):
-            # we can't pass these in kwargs because formfield() strips them out
-            form_field.enum = self.enum
-            form_field.strict = self.strict
-            form_field.primitive = self.primitive
-        # pragma: no cover
+        form_field.enum = self.enum
+        form_field.strict = self.strict
+        form_field.primitive = self.primitive
         return form_field
 
     def get_choices(
@@ -1239,7 +1236,6 @@ def contribute_to_class(
 
     def formfield(self, form_class=None, choices_form_class=None, **kwargs):
         from django_enum.forms import (
-            ChoiceFieldMixin,
             EnumFlagField,
             FlagSelectMultiple,
             NonStrictFlagSelectMultiple,
@@ -1261,11 +1257,9 @@ def formfield(self, form_class=None, choices_form_class=None, **kwargs):
         )
 
         # we can't pass these in kwargs because formfield() strips them out
-        if isinstance(form_field, ChoiceFieldMixin):
-            form_field.enum = self.enum
-            form_field.strict = self.strict
-            form_field.primitive = self.primitive
-        # pragma: no cover
+        form_field.enum = self.enum  # type: ignore
+        form_field.strict = self.strict  # type: ignore
+        form_field.primitive = self.primitive  # type: ignore
         return form_field
 
     def get_choices(