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>

scripts/restart-server

@@ -1,16 +1,16 @@
 #!/usr/bin/env python3
 import argparse
 import configparser
-import os
-import sys
-import pwd
-import subprocess
 import logging
-import time
+import os
+import pwd
 import shlex
+import subprocess
+import sys
+import time
 
 sys.path.append(os.path.join(os.path.dirname(__file__), '..'))
-from scripts.lib.zulip_tools import ENDC, OKGREEN, WARNING, DEPLOYMENTS_DIR, overwrite_symlink
+from scripts.lib.zulip_tools import DEPLOYMENTS_DIR, ENDC, OKGREEN, WARNING, overwrite_symlink
 
 logging.Formatter.converter = time.gmtime
 logging.basicConfig(format="%(asctime)s restart-server: %(message)s",