Replace deprecated "auth_uri" by "www_authenticate_uri"
According to [1], "auth_uri" has been deprecated.
This patch replace it by using "www_authenticate_uri" instead.
[1]
# *not* be the same endpoint the service user utilizes for validating tokens,
# because normal end users may not be able to reach that endpoint. (string
# value)
-#auth_uri = <None>
+#www_authenticate_uri = <None>
# API version of the admin Identity API endpoint. (string value)
#auth_version = <None>
