[Meta] Switch away from nose test framework

[d-ylee]

Impact of the new feature
nose's website shows that it is in maintenance mode and needs someone to maintain it.

Is your feature request related to a problem? Please describe.
Modernize the testing framework.

Describe the solution you'd like
Evaluate pytest, nose2, or other alternatives, and determine which is easier to implement.

Describe alternatives you've considered
Continue using nose

Additional context
Our current unittests do import nose, but only for the nose.plugins.attrib and nose.SkipTest, which could potentially be replaced with pytest.mark and pytest.mark.skip, respectively. More investigation would be needed.