Update hacking for Focal

As per victoria cycle testing runtime and community goal[1]
we need to migrate upstream CI/CD to Ubuntu Focal(20.04).

This bumps hacking to 3.2.0 in order to work with focal, disabling W504
to align with neutron (W503 is enabled in this version)

Story: #2007865
Task: #40199

[1] https://governance.openstack.org/tc/goals/selected/victoria/migrate-ci-cd-jobs-to-ubuntu-focal.html

Change-Id: Ic7a6da941172aae6dc504eb377c3e94de4805a89
diff --git a/neutron_tempest_plugin/api/base.py b/neutron_tempest_plugin/api/base.py
index 1b02211..77bf5e8 100644
--- a/neutron_tempest_plugin/api/base.py
+++ b/neutron_tempest_plugin/api/base.py
@@ -478,7 +478,7 @@
         """
 
         if not cls.try_reserve_subnet_cidr(addr, **ipnetwork_kwargs):
-            raise ValueError('Subnet CIDR already reserved: %r'.format(
+            raise ValueError('Subnet CIDR already reserved: {0!r}'.format(
                 addr))
 
     @classmethod