[REQ] Update python test dependencies

[yurinnick]

Is your feature request related to a problem? Please describe.

Python clients get generated with old and unsupported testing dependencies:

• randomize Last released: Oct 16, 2016
• nose Last released: Jun 2, 2015

Consider that this dependencies may not be compatible with Python 3 while Python 2 will be officially unsupported 01.2020

Describe the solution you'd like

Update to a modern libraries with similar functionality:

• nose2
• nose-randomly
• randomly

[wing328]

@yurinnick I wonder if you can file a PR to help update the libraries to the latest stable version.

[spacether]

Another solution here would be to switch from nose to pytest.
It is actively maintained per pypi: https://pypi.org/project/pytest/#history

More people/projects may prefer it per the number of github stars.
Pytest: https://github.com/pytest-dev/pytest 5.2k stars
Nose: https://github.com/nose-devs/nose 1.3k stars