[SEBA-412] Automated reformat of Python code

Passes of modernize, autopep8, black, then check with flake8

flake8 + manual fixes:
  lib/xos-config
  lib/xos-kafka
  lib/xos-util
  xos/coreapi
  xos/api
  xos/xos_client

Change-Id: Ib23cf84cb13beb3c6381fa0d79594dc9131dc815
diff --git a/lib/xos-genx/xos-genx-tests/attics/xosmodel_header.py b/lib/xos-genx/xos-genx-tests/attics/xosmodel_header.py
index 5cee4a3..9ac13cc 100644
--- a/lib/xos-genx/xos-genx-tests/attics/xosmodel_header.py
+++ b/lib/xos-genx/xos-genx-tests/attics/xosmodel_header.py
@@ -1,4 +1,3 @@
-
 # Copyright 2017-present Open Networking Foundation
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
@@ -15,4 +14,4 @@
 
 
 def header():
-    return 'header'
+    return "header"