Remove the fixed timestamp used for testing

Author: brichet

packages/jupyterlab-collaborative-chat/jupyterlab_collaborative_chat/ychat.py

@@ -119,8 +119,7 @@ def _timestamp_new_messages(self, event: ArrayEvent) -> None:
         # flag is set to False after first reading.
         if self.dirty:
             return
-        # timestamp: float = time.time()
-        timestamp: float = 1715619678
+        timestamp: float = time.time()
         index = 0
         inserted_count = -1
         deleted_count = -1