support/graph-size: fix flake8 warnings

support/graph-size: fix flake8 warnings

There are three E501 warnings returned by flake8, when run locally,
because we enforce a local 80-char limit, but that are not reported by
the gitlab-ci jobs because only a 132-char limit is required there.

Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>
Cc: Ricardo Martincoski <ricardo.martincoski@gmail.com>
Cc: Arnout Vandecappelle <arnout@mind.be>
Cc: Thomas De Schampheleire <thomas.de_schampheleire@nokia.com>
Reviewed-by: Ricardo Martincoski <ricardo.martincoski@gmail.com>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>