enhance: [2.4]describecollection output add created_timestamp (#2620)

enhance: describecollection output add created_timestamp
issue: #2617
pr: #2618

Signed-off-by: Xianhui.Lin <xianhui.lin@zilliz.com>

Author: JsDove

pymilvus/client/abstract.py

@@ -123,7 +123,7 @@ def __init__(self, raw: Any):
         self.num_shards = 0
         self.num_partitions = 0
         self.enable_dynamic_field = False
-        self.update_timestamp = 0
+        self.created_timestamp = 0
         if self._raw:
             self.__pack(self._raw)
 
@@ -134,7 +134,7 @@ def __pack(self, raw: Any):
         self.collection_id = raw.collectionID
         self.num_shards = raw.shards_num
         self.num_partitions = raw.num_partitions
-
+        self.created_timestamp = raw.created_timestamp
         # keep compatible with older Milvus
         try:
             self.consistency_level = raw.consistency_level
@@ -182,6 +182,9 @@ def dict(self):
             "num_partitions": self.num_partitions,
             "enable_dynamic_field": self.enable_dynamic_field,
         }
+
+        if self.created_timestamp != 0:
+            _dict["created_timestamp"] = self.created_timestamp
         self._rewrite_schema_dict(_dict)
         return _dict