[Python] Add configuration.{connection_pool_maxsize, assert_hostname} (#6508)

* Backport kubernetes client features:

- assert_hostname
- connection_pool_maxsize
- cleanups

* Update petstore sample

samples/client/petstore/python-asyncio/setup.py

@@ -0,0 +1,42 @@
+# coding: utf-8
+
+"""
+    Swagger Petstore
+
+    This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\
+
+    OpenAPI spec version: 1.0.0
+    Contact: apiteam@swagger.io
+    Generated by: https://github.com/swagger-api/swagger-codegen.git
+"""
+
+
+import sys
+from setuptools import setup, find_packages
+
+NAME = "petstore-api"
+VERSION = "1.0.0"
+# To install the library, run the following
+#
+# python setup.py install
+#
+# prerequisite: setuptools
+# http://pypi.python.org/pypi/setuptools
+
+REQUIRES = ["urllib3 >= 1.15", "six >= 1.10", "certifi", "python-dateutil"]
+REQUIRES.append("aiohttp")
+
+setup(
+    name=NAME,
+    version=VERSION,
+    description="Swagger Petstore",
+    author_email="apiteam@swagger.io",
+    url="",
+    keywords=["Swagger", "Swagger Petstore"],
+    install_requires=REQUIRES,
+    packages=find_packages(),
+    include_package_data=True,
+    long_description="""\
+    This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\
+    """
+)