python: add pylint to pipenv

python: add pylint to pipenv

We are specifying >= pylint 2.8.x for several reasons:

1. For setup.cfg support, added in pylint 2.5.x
2. To specify a version that has incompatibly dropped
   bad-whitespace checks (2.6.x)
3. 2.7.x fixes "unsubscriptable" warnings in Python 3.9
4. 2.8.x adds a new, incompatible 'consider-using-with'
   warning that must be disabled in some cases.
   These pragmas cause warnings themselves in 2.7.x.

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Cleber Rosa <crosa@redhat.com>
Tested-by: Cleber Rosa <crosa@redhat.com>
Message-id: 20210527211715.394144-18-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>