Remove remnants of Python 2 support code.

picklefield/constants.py

@@ -1,3 +1 @@
-from __future__ import unicode_literals
-
 DEFAULT_PROTOCOL = 3

picklefield/fields.py

@@ -1,7 +1,6 @@
-from __future__ import unicode_literals
-
 from base64 import b64decode, b64encode
 from copy import deepcopy
+from pickle import dumps, loads
 from zlib import compress, decompress
 
 from django import VERSION as DJANGO_VERSION
@@ -11,11 +10,6 @@
 
 from .constants import DEFAULT_PROTOCOL
 
-try:
-    from cPickle import loads, dumps  # pragma: no cover
-except ImportError:
-    from pickle import loads, dumps  # pragma: no cover
-
 
 class PickledObject(str):
     """

tests/models.py

@@ -1,5 +1,3 @@
-from __future__ import unicode_literals
-
 from datetime import date
 
 from django.db import models

tests/settings.py

@@ -1,5 +1,3 @@
-from __future__ import unicode_literals
-
 SECRET_KEY = 'not-anymore'
 
 DATABASES = {

tests/tests.py

@@ -1,5 +1,6 @@
 import json
 from datetime import date
+from unittest.mock import patch
 
 from django.core import checks, serializers
 from django.db import IntegrityError, models
@@ -14,18 +15,13 @@
     TestCustomDataType, TestingModel,
 )
 
-try:
-    from unittest.mock import patch  # pragma: no cover
-except ImportError:
-    from mock import patch  # pragma: no cover
-
 
 class PickledObjectFieldTests(TestCase):
     def setUp(self):
         self.testing_data = (D2, S1, T1, L1,
                              TestCustomDataType(S1),
                              MinimalTestingModel)
-        return super(PickledObjectFieldTests, self).setUp()
+        return super().setUp()
 
     def test_data_integrity(self):
         """