pylint: remove unused imports

chrono/manager/widgets.py

@@ -11,11 +11,9 @@ import json
 import re
 import uuid
 
-from django.forms import widgets
 from django.forms.widgets import DateTimeInput, DateInput, TimeInput
 from django.utils.formats import get_language
 from django.utils.safestring import mark_safe
-from django.utils.six import string_types
 
 DATE_FORMAT_JS_PY_MAPPING = {
     'P': '%p',