Use datetime.utcnow() instead of datetime.now()

(suggested in @spulec review)

moto/swf/models/activity_task.py

@@ -25,7 +25,7 @@ class ActivityTask(object):
         self.workflow_execution = workflow_execution
         # this is *not* necessarily coherent with workflow execution history,
         # but that shouldn't be a problem for tests
-        self.scheduled_at = datetime.now()
+        self.scheduled_at = datetime.utcnow()
 
     def _check_workflow_execution_open(self):
         if not self.workflow_execution.open:

moto/swf/models/decision_task.py

@@ -21,7 +21,7 @@ class DecisionTask(object):
         self.state = "SCHEDULED"
         # this is *not* necessarily coherent with workflow execution history,
         # but that shouldn't be a problem for tests
-        self.scheduled_at = datetime.now()
+        self.scheduled_at = datetime.utcnow()
         self.timeout_type = None
 
     @property

moto/swf/utils.py

@@ -6,4 +6,4 @@ def decapitalize(key):
     return key[0].lower() + key[1:]
 
 def now_timestamp():
-    return float(mktime(datetime.now().timetuple()))
+    return float(mktime(datetime.utcnow().timetuple()))