Add isort pre-commit hook

Sort import statement in python files

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

api/libretimeapi/models/authentication.py

@@ -1,11 +1,13 @@
 import hashlib
+
 from django.contrib import auth
 from django.contrib.auth.models import AbstractBaseUser, Permission
 from django.core.exceptions import PermissionDenied
 from django.db import models
 from libretimeapi.managers import UserManager
 from libretimeapi.permission_constants import GROUPS
-from .user_constants import USER_TYPES, ADMIN
+
+from .user_constants import ADMIN, USER_TYPES
 
 
 class LoginAttempt(models.Model):

api/libretimeapi/models/playlists.py

@@ -1,4 +1,5 @@
 from django.db import models
+
 from .files import File
 from .smart_blocks import SmartBlock
 

api/libretimeapi/models/playout.py

@@ -1,4 +1,5 @@
 from django.db import models
+
 from .files import File
 
 

api/libretimeapi/models/podcasts.py

@@ -1,4 +1,5 @@
 from django.db import models
+
 from .authentication import User
 from .files import File
 

api/libretimeapi/models/schedule.py

@@ -1,4 +1,5 @@
 from django.db import models
+
 from .files import File
 
 

api/libretimeapi/models/shows.py

@@ -1,6 +1,7 @@
 from django.db import models
-from .playlists import Playlist
+
 from .files import File
+from .playlists import Playlist
 
 
 class Show(models.Model):

api/libretimeapi/models/tracks.py

@@ -1,4 +1,5 @@
 from django.db import models
+
 from .files import File
 
 

api/libretimeapi/models/webstreams.py

@@ -1,5 +1,6 @@
-from django.db import models
 from django.contrib.auth import get_user_model
+from django.db import models
+
 from .schedule import Schedule