[lint] relax black version requirement

Summary:
Black stopped supporting python3.6 as of version 22.9.0

This is a hack so that people with python 3.6 don't get an error when running arc lint or arc diff. It allows people with e.gG Ubuntu 18.04 to contribute, as long as they don't touch python code and don't run arc lint --everything (black 22.8 yields a different style for long strings and multiline strings).

Test Plan: Make sure arc lint works with black==22.8.0 installed

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Differential Revision: https://reviews.bitcoinabc.org/D13922