Describe the bug
As can be seen here: https://github.com/Project-MONAI/MONAI/runs/4802838071,
the .runtests.sh passes (the job named flake8), yet the tests fail, due to missing imports: https://github.com/Project-MONAI/MONAI/runs/4802838468?check_suite_focus=true#step:10:11980.

Expected behavior
Our runtests.sh script should pick up on these.