Remove more python2 stuff

InvenTree/users/admin.py

@@ -1,5 +1,3 @@
-# -*- coding: utf-8 -*-
-from __future__ import unicode_literals
 
 from django.utils.translation import gettext_lazy as _
 

InvenTree/users/api.py

@@ -1,6 +1,3 @@
-# -*- coding: utf-8 -*-
-
-from __future__ import unicode_literals
 
 from django.contrib.auth.models import User
 from django.core.exceptions import ObjectDoesNotExist

InvenTree/users/apps.py

@@ -1,6 +1,3 @@
-# -*- coding: utf-8 -*-
-from __future__ import unicode_literals
-
 from django.db.utils import OperationalError, ProgrammingError
 
 from django.apps import AppConfig

InvenTree/users/tests.py

@@ -1,6 +1,3 @@
-# -*- coding: utf-8 -*-
-from __future__ import unicode_literals
-
 from django.test import TestCase
 from django.apps import apps
 from django.urls import reverse