python: Sort imports with isort.

Fixes #2665.

Regenerated by tabbott with `lint --fix` after a rebase and change in
parameters.

Note from tabbott: In a few cases, this converts technical debt in the
form of unsorted imports into different technical debt in the form of
our largest files having very long, ugly import sequences at the
start.  I expect this change will increase pressure for us to split
those files, which isn't a bad thing.

Signed-off-by: Anders Kaseorg <anders@zulip.com>

zilencer/views.py

@@ -1,29 +1,46 @@
-from typing import Any, Dict, List, Optional, Union
 import datetime
 import logging
+from typing import Any, Dict, List, Optional, Union
 
 from django.core.exceptions import ValidationError
-from django.core.validators import validate_email, URLValidator
+from django.core.validators import URLValidator, validate_email
 from django.db import IntegrityError, transaction
 from django.http import HttpRequest, HttpResponse
 from django.utils import timezone
-from django.utils.translation import ugettext as _, ugettext as err_
+from django.utils.translation import ugettext as _
+from django.utils.translation import ugettext as err_
 from django.views.decorators.csrf import csrf_exempt
 
 from analytics.lib.counts import COUNT_STATS
-from zerver.decorator import require_post, InvalidZulipServerKeyError
+from zerver.decorator import InvalidZulipServerKeyError, require_post
 from zerver.lib.exceptions import JsonableError
-from zerver.lib.push_notifications import send_android_push_notification, \
-    send_apple_push_notification
+from zerver.lib.push_notifications import (
+    send_android_push_notification,
+    send_apple_push_notification,
+)
 from zerver.lib.request import REQ, has_request_variables
 from zerver.lib.response import json_error, json_success
-from zerver.lib.validator import check_int, check_string, \
-    check_capped_string, check_string_fixed_length, check_float, check_none_or, \
-    check_dict_only, check_list, check_bool
+from zerver.lib.validator import (
+    check_bool,
+    check_capped_string,
+    check_dict_only,
+    check_float,
+    check_int,
+    check_list,
+    check_none_or,
+    check_string,
+    check_string_fixed_length,
+)
 from zerver.models import UserProfile
 from zerver.views.push_notifications import validate_token
-from zilencer.models import RemotePushDeviceToken, RemoteZulipServer, \
-    RemoteRealmCount, RemoteInstallationCount, RemoteRealmAuditLog
+from zilencer.models import (
+    RemoteInstallationCount,
+    RemotePushDeviceToken,
+    RemoteRealmAuditLog,
+    RemoteRealmCount,
+    RemoteZulipServer,
+)
+
 
 def validate_entity(entity: Union[UserProfile, RemoteZulipServer]) -> RemoteZulipServer:
     if not isinstance(entity, RemoteZulipServer):