Update flake8 check configuration
This MR updates the flake8
lint check to workaround https://github.com/tylerwince/flake8-bandit/issues/33 (closes #84 (closed)) and to not fail the CI job when lint is found.
Now if the flake8 CI job fails, that indicates that the linter failed to run, which is bad, but not that lint was found. This is instead highlighted on the Code Quality widget on the MR interface.