fix isort complain

formset/widgets.py

@@ -10,10 +10,9 @@
 from django.core.files.uploadedfile import UploadedFile
 from django.core.signing import get_cookie_signer
 from django.db.models.query_utils import Q
-from django.forms.widgets import FILE_INPUT_CONTRADICTION
 from django.forms.models import ModelChoiceIterator, ModelChoiceIteratorValue
 from django.forms.widgets import (DateTimeBaseInput, FileInput, FILE_INPUT_CONTRADICTION, Select, SelectMultiple,
-    TextInput, Widget)
+                                  TextInput, Widget)
 from django.template.loader import get_template
 from django.utils.encoding import uri_to_iri
 from django.utils.functional import cached_property