[Python] Fix issue with CI due to dependency (#4716)

* Issue 4637 Fix for ci build (#4643)

* [Python] update python requirement.txt and use single quote for safe characters (#4702)

* update python requirement

* update petstore sample

samples/client/petstore/python/test/test_capitalization.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
+"""
+
+
+from __future__ import absolute_import
+
+import os
+import sys
+import unittest
+
+import petstore_api
+from petstore_api.rest import ApiException
+from petstore_api.models.capitalization import Capitalization
+
+
+class TestCapitalization(unittest.TestCase):
+    """ Capitalization unit test stubs """
+
+    def setUp(self):
+        pass
+
+    def tearDown(self):
+        pass
+
+    def testCapitalization(self):
+        """
+        Test Capitalization
+        """
+        model = petstore_api.models.capitalization.Capitalization()
+
+
+if __name__ == '__main__':
+    unittest.main()