As of pip 10.0, --allow-unverified is not permitted.
Use of the flag in this repo was previously used to force
installation of python-apt to accommodate certain unit tests.
The unverified package, python-apt, is no longer necessary
for test execution.
Related-Bug: #1760720
Change-Id: I6aca0d4c6a863d5cc5da556cff56e5fde5d335d3