As discussed at the Epoxy PTG meeting, run an automated
upgrade tool to make code python 3.9+ compliant.
Result of running:
$ pyupgrade --py39-plus $(git ls-files | grep ".py$")
Fixed PEP8 errors introduced by pyupgrade by running:
$ autopep8 --select=E127,E128,E501 --max-line-length 79 -r \
--in-place neutron_lib
Also did manual updates as necessary to fix other errors
and warnings after above commands. Removed a number of
pylint 'disable' directives.
Inspired by Octavia and Nova [0].
[0] https://review.opendev.org/c/openstack/nova/+/896986
Change-Id: Ic8c95898fc00d5463aa0992e844eee60ac3dc5a0