clean up / format / poetry (#1000)

* stub in poetry for pipenv

* re-add tester image

* add pre-commit / formatting

* fix ghactions

* revert test data whitespace, exclude tests/data

* revert ws

* decruft, rm tox/pipenv

* install dev packages for base image

* add lgtm config to force to py3

tests/test_cors.py

@@ -1,6 +1,3 @@
-from django.test import TestCase, Client
-from peeringdb_server.models import Organization, User
-from .util import ClientCase
 from corsheaders.middleware import (
     ACCESS_CONTROL_ALLOW_CREDENTIALS,
     ACCESS_CONTROL_ALLOW_HEADERS,
@@ -9,6 +6,11 @@ from corsheaders.middleware import (
     ACCESS_CONTROL_EXPOSE_HEADERS,
     ACCESS_CONTROL_MAX_AGE,
 )
+from django.test import Client, TestCase
+
+from peeringdb_server.models import Organization, User
+
+from .util import ClientCase
 
 
 class CorsTest(ClientCase):