Commit ae74f71a1e9d4be043162b19d23f2d44c964c771 removed the flake8
unittest and commit 3428a65b1cd644445f55ad8ae65ece5f73d7acb5 added
running flake8 again, but only for files named `*.py`.
Check also all Python scripts with a Python shebang.
Signed-off-by: Benjamin Drung <benjamin.drung@canonical.com>