Fix ValueError exception on relative import

test_job raised an exception:

ValueError: Attempted relative import in non-package

tests/test_job.py

@@ -5,7 +5,7 @@ from __future__ import (absolute_import, division, print_function,
 from datetime import datetime
 import time
 
-from tests import RQTestCase
+from tests import RQTestCase, fixtures
 from tests.helpers import strip_microseconds
 
 from rq.compat import PY2, as_text
@@ -16,7 +16,7 @@ from rq.registry import DeferredJobRegistry
 from rq.utils import utcformat
 from rq.worker import Worker
 
-from . import fixtures
+
 
 try:
     from cPickle import loads, dumps