Enforce pylint on payload_utils.

- Skipping proto_converters for now.

BUG=chromium:1092516
TEST=CQ
TEST=repo upload outside chroot
TEST=repo upload inside chroot

Change-Id: I1263731c8425d6ba143e669b13de1eb909971935
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/config/+/2236575
Commit-Queue: Andrew Lamb <andrewlamb@chromium.org>
Tested-by: Andrew Lamb <andrewlamb@chromium.org>
Reviewed-by: Sean McAllister <smcallis@google.com>
diff --git a/payload_utils/checker/io_utils.py b/payload_utils/checker/io_utils.py
index 7b50dcd..ee43989 100644
--- a/payload_utils/checker/io_utils.py
+++ b/payload_utils/checker/io_utils.py
@@ -8,11 +8,12 @@
 
 from typing import Any, Dict
 
-from chromiumos.config.payload import config_bundle_pb2
-
 from google.protobuf import json_format
 from google.protobuf.message import Message
 
+from chromiumos.config.payload import config_bundle_pb2
+
+
 
 def write_message_json(message: Message, path: pathlib.Path, \
                        default_fields=False):