networking-bgpvpn/bgpvpn_dashboard at 36fc780b2ab65054f34d3d640d6480ee4f65ea20 - networking-bgpvpn - OpenDev: Free Software Needs Free Tools

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 networking_bgpvpn
Also did manual updates as necessary to fix other errors
and warnings after above commands.
Inspired by Octavia and Nova [0].
[0] https://review.opendev.org/c/openstack/nova/+/896986
Change-Id: Iac7a039ad6924de14aba8f391ff904785c089df7