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>

zerver/views/compatibility.py

@@ -1,13 +1,14 @@
-from django.http import HttpResponse, HttpRequest
 import re
 from typing import List, Optional, Tuple
 
+from django.http import HttpRequest, HttpResponse
 from django.utils.translation import ugettext as _
 
+from version import DESKTOP_MINIMUM_VERSION, DESKTOP_WARNING_VERSION
 from zerver.lib.response import json_error, json_success
 from zerver.lib.user_agent import parse_user_agent
 from zerver.signals import get_device_browser
-from version import DESKTOP_MINIMUM_VERSION, DESKTOP_WARNING_VERSION
+
 
 def pop_numerals(ver: str) -> Tuple[List[int], str]:
     match = re.search(r'^( \d+ (?: \. \d+ )* ) (.*)', ver, re.X)