Fix pep8 errors
diff --git a/tests/conftest.py b/tests/conftest.py
index 6ba8ae0..d55e6cf 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -17,7 +17,7 @@
 
 from cryptography.hazmat.backends import _available_backends
 from cryptography.hazmat.backends.interfaces import (
-    CipherBackend, CMACBackend, DSABackend, HMACBackend, HashBackend,
+    CMACBackend, CipherBackend, DSABackend, HMACBackend, HashBackend,
     PBKDF2HMACBackend, RSABackend
 )
 from .utils import check_backend_support, check_for_iface, select_backends