improve tests health (flake8 warnings)

tests/test_replicaset_connection.py

@@ -1,7 +1,6 @@
 import unittest
 
-from pymongo import MongoClient
-from pymongo import ReadPreference
+from pymongo import MongoClient, ReadPreference
 
 import mongoengine
 from mongoengine.connection import ConnectionFailure
@@ -25,14 +24,13 @@ class ConnectionTest(unittest.TestCase):
     def test_replicaset_uri_passes_read_preference(self):
         """Requires a replica set called "rs" on port 27017
         """
-
         try:
             conn = mongoengine.connect(
                 db="mongoenginetest",
                 host="mongodb://localhost/mongoenginetest?replicaSet=rs",
                 read_preference=READ_PREF,
             )
-        except ConnectionFailure as e:
+        except ConnectionFailure:
             return
 
         if not isinstance(conn, CONN_CLASS):