Bump hacking min version to 3.0.1
Bump hacking min version to 3.0.1

hacking 3.0.1 fix the pinning of flake8 to avoid bringing in a new
version with new checks.

bumping the min version for hacking so that any older hacking versions
which auto adopt the new checks are not used.

Change-Id: I8189569f3f9f770bf623fabbdee2ef5dc0554d84

openstack/ceilometer,openstack/ceilometer