Ignore lint check on randbytes since it's wrapped in a version check

Summary:
With Python 3.8 and below, the linter complains that random does not have randbytes as an attribute.
This is fine since random.randbytes is wrapped in a version check. This patch makes the linter ignore
that.

Depends on D11654

Test Plan:

arc lint

Reviewers: #bitcoin_abc, PiRK

Reviewed By: #bitcoin_abc, PiRK

Differential Revision: https://reviews.bitcoinabc.org/D11655