This bumps the version of flake8 and pycodestyle to something much
newer, which resolves a long-standing warning about nested sets and
allows us to use new fangled features like f-strings if we so choose.
Note that this requires some minor modifications to keep the 'pep8' task
passing.
Change-Id: I3af8eb490345a6152372730ca3e0a6702bf482ea
Signed-off-by: Stephen Finucane <sfinucan@redhat.com>