Fix the hacking errors present since neutron-lib 3.21.1

This new neutron-lib 3.21.1 version includes several new hacking checks.
Because the eventlet removal is not finished, the N535 is skipped.

Signed-off-by: Rodolfo Alonso Hernandez <ralonsoh@redhat.com>
Change-Id: Iaad3e87874838eb75d2f6789e71030eda8c587a0
9 files changed