Current test framework constrains Python to < 3.10

[ajnelson-nist]

#130 tried to expand the Python testing to 3.11. However, nose, which appears to not have been maintained for some time, references a class in the python stdlib that is no longer present (or aliased), causing testing to fail. 130 includes references on the particular class.

It appears the tests should switch to another framework in order to run on Python versions later than 3.9.