Fix pep8 Zuul failure

A new version of flake8 (6.0.0) was released Nov 23, 2022
It is leading to an argparse error
  ValueError: 'string' is not callable

The fix is to use 'hacking' which is an openstack module
that pulls in the appropriate version of flake8.

Closes-Bug: #1997971
Signed-off-by: Al Bailey <al.bailey@windriver.com>
Change-Id: Icaa5cd1cb7c362bd8caf666d82d7d7f655523fb0

openstack/python-horizon/centos/files/guni_config.py

@@ -1,3 +1,10 @@
+"""
+Copyright (c) 2022 Wind River Systems, Inc.
+
+SPDX-License-Identifier: Apache-2.0
+
+"""
+
 import datetime
 import fnmatch
 import os

test-requirements.txt

@@ -1,5 +1,8 @@
+# The order of packages is significant, because pip processes them in the order
+# of appearance.
+# always put 'hacking' first.  it pulls in flake8, etc..
+hacking < 4.0.1
 bashate
 PyYAML
 yamllint
-flake8
 flake8-import-order