Refs #23919 -- Removed most of remaining six usage

Thanks Tim Graham for the review.

django/core/validators.py

@@ -1,12 +1,12 @@
 import os
 import re
+from urllib.parse import urlsplit, urlunsplit
 
 from django.core.exceptions import ValidationError
 from django.utils.deconstruct import deconstructible
 from django.utils.encoding import force_text
 from django.utils.functional import SimpleLazyObject
 from django.utils.ipv6 import is_valid_ipv6_address
-from django.utils.six.moves.urllib.parse import urlsplit, urlunsplit
 from django.utils.translation import ugettext_lazy as _, ungettext_lazy
 
 # These values, if given to validate(), will trigger the self.required check.