Update tests to run using python 3.8. Exclude quality tests for python 3.8. Update toxenv to use the specified python version inside the container.
Update tests to run using python 3.8.
Exclude quality tests for python 3.8.
Update toxenv to use the specified python version inside the container.

EDUlib/xqueue,EDUlib/xqueue,edx/xqueue,EDUlib/xqueue,edx/xqueue,edx/xqueue