Add isort pre-commit hook

Sort import statement in python files

See https://github.com/PyCQA/isort

api/libretimeapi/tests/test_models.py

@@ -1,9 +1,9 @@
-from rest_framework.test import APITestCase
-from django.contrib.auth.models import Group
 from django.apps import apps
+from django.contrib.auth.models import Group
 from libretimeapi.models import User
-from libretimeapi.models.user_constants import GUEST, DJ
+from libretimeapi.models.user_constants import DJ, GUEST
 from libretimeapi.permission_constants import GROUPS
+from rest_framework.test import APITestCase
 
 
 class TestUserManager(APITestCase):

api/libretimeapi/tests/test_permissions.py

@@ -1,16 +1,17 @@
 import os
+
+from django.conf import settings
 from django.contrib.auth import get_user_model
 from django.contrib.auth.models import AnonymousUser
-from django.conf import settings
-from rest_framework.test import APITestCase, APIRequestFactory
-from model_bakery import baker
-from libretimeapi.permissions import IsSystemTokenOrUser
+from libretimeapi.models.user_constants import ADMIN, DJ, GUEST, PROGRAM_MANAGER
 from libretimeapi.permission_constants import (
-    GUEST_PERMISSIONS,
     DJ_PERMISSIONS,
+    GUEST_PERMISSIONS,
     PROGRAM_MANAGER_PERMISSIONS,
 )
-from libretimeapi.models.user_constants import GUEST, DJ, PROGRAM_MANAGER, ADMIN
+from libretimeapi.permissions import IsSystemTokenOrUser
+from model_bakery import baker
+from rest_framework.test import APIRequestFactory, APITestCase
 
 
 class TestIsSystemTokenOrUser(APITestCase):

api/libretimeapi/tests/test_views.py

@@ -1,9 +1,10 @@
 import os
-from django.contrib.auth.models import AnonymousUser
+
 from django.conf import settings
-from rest_framework.test import APITestCase, APIRequestFactory
-from model_bakery import baker
+from django.contrib.auth.models import AnonymousUser
 from libretimeapi.views import FileViewSet
+from model_bakery import baker
+from rest_framework.test import APIRequestFactory, APITestCase
 
 
 class TestFileViewSet(APITestCase):