SUBMARINE-432. [SDK] test_verify_rest_response is flaky in python 3.5

[pingsutw]

What is this PR for?

Fix test failure in python3.5
if we use python3.5 str({'a': 200, 'b': 2, 'c': 3}) will output different order like {'b': 2, 'c': 3, 'a': 200}
change to str(json object) will fix it.

with pytest.raises(RestException, match=str(mock_json_body)):
verify_rest_response(mock_response, '/api/v1/jobs')
E AssertionError: Pattern '{'b': 2, 'c': 3, 'a': 200}' not found in 'None: Response: {'c': 3, 'a': 200, 'b': 2}'

What type of PR is it?

[Bug Fix]

Todos

• - Task

What is the Jira issue?

https://issues.apache.org/jira/browse/SUBMARINE-432

How should this be tested?

https://travis-ci.org/github/pingsutw/hadoop-submarine/builds/663060104
https://github.com/pingsutw/hadoop-submarine/runs/511082403

Screenshots (if appropriate)

Questions:

• Does the licenses files need update? No
• Is there breaking changes for older versions? No
• Does this needs documentation? No

[xunliu]

LGTM

[pingsutw]

@liuxunorg Thanks for the review and commit.