using default mutable argument is wrong

we can use a tuple instead

Change-Id: Ic807a8b740e022fc6d4556dd83d999a2395b9748

vitrageclient/v1/alarm.py

@@ -58,8 +58,8 @@ class Alarm(object):
                 start=None,
                 end=None,
                 limit=1000,
-                sort_by=['start_timestamp', 'vitrage_id'],
-                sort_dirs=['asc', 'asc'],
+                sort_by=('start_timestamp', 'vitrage_id'),
+                sort_dirs=('asc', 'asc'),
                 filter_by=None,
                 filter_vals=None,
                 next_page=True,