Fix typo in api_client.mustache "configuraiton -> configuration" (#15050)

Author: md-mq

modules/openapi-generator/src/main/resources/python-nextgen/api_client.mustache

@@ -56,7 +56,7 @@ class ApiClient(object):
 
     def __init__(self, configuration=None, header_name=None, header_value=None,
                  cookie=None, pool_threads=1):
-        # use default configuraiton if none is provided
+        # use default configuration if none is provided
         if configuration is None:
             configuration = Configuration.get_default()
         self.configuration = configuration