Remove Flake8 from lgtm.yml

[sj]

LGTM.com performs its own checks by running queries over source code (all queries are open source on GitHub). It does not show alerts that are generated by Flake.

Unfortunately the provided Flake commands actually return an error, which means that LGTM's Python analysis fails:

[2019-01-05 07:31:29] [build] ++ python3 -m flake8 . --count --select=E901,E999,F821,F822,F823 --show-source --statistics
[2019-01-05 07:31:35] [build] ./regression-tests.recursor-dnssec/test_ECS.py:521:99: F821 undefined name 'cls'
[2019-01-05 07:31:35] [build]             additional = dns.rrset.from_text('ns1.ecs-echo.example.', 15, dns.rdataclass.IN, 'A', cls._PREFIX + '.21')
[2019-01-05 07:31:35] [build]

(https://lgtm.com/projects/g/PowerDNS/pdns/logs/rev/3a0387f7429710a21af7abcc745c71d6932e14be/lang:python/stage:Build%20child%20(3a0387f))

[rgacogne]

Note that we should also fix https://github.com/PowerDNS/pdns/blob/master/regression-tests.recursor-dnssec/test_ECS.py#L521 which is clearly wrong.

[sj]

I think PowerDNS used to have automated code review for pull requests, but it seems that the token for that got revoked:

(see https://lgtm.com/projects/g/PowerDNS/pdns/ci/)

[Habbie]

Yes - LGTM kept commenting as me, and I could not find a way to make it stop doing that. I tried giving it permission via another account but that apparently did not work.

[sj]

Ah, I see. No worries: the GitHub Apps API integration should be here soon. That comes with built-in support for an LGTM bot account 🙂

[Habbie]

Note that we should also fix https://github.com/PowerDNS/pdns/blob/master/regression-tests.recursor-dnssec/test_ECS.py#L521 which is clearly wrong.

This suggests that we should add flake8 testing to something else, like Travis.