update dm.now

csst_common/data_manager.py

@@ -287,7 +287,8 @@ class CsstMsDataManager:
 
     @staticmethod
     def now():
-        return datetime.datetime.now().strftime('%Y-%m-%d %H:%M:%S')
+        """ Return ISOT8601 format datetime. """
+        return datetime.datetime.now().strftime('%Y-%m-%dT%H:%M:%S.%f')
 
     # DFS APIs
     @property