fix: rename member content var in on_tool_call_completed to satisfy mypy

The member branch bound the member snapshot dict to `content`, which the
non-member path later reassigns to a JSON string, tripping a mypy
assignment-type error after the rebase onto latest main.

Author: ProgrammerPlus1998

libs/agno/agno/os/interfaces/agui/handlers.py

@@ -240,9 +240,9 @@ def on_tool_call_completed(chunk: BaseRunOutputEvent, state: StreamState) -> Lis
         return events
 
     if _is_member_chunk(chunk):
-        _, content = state.get_or_create_member(_member_key(chunk))
-        content["status"] = "running"
-        content["currentTool"] = None
+        _, member_content = state.get_or_create_member(_member_key(chunk))
+        member_content["status"] = "running"
+        member_content["currentTool"] = None
         return [_member_activity_snapshot(chunk, state)]
 
     if tool.tool_call_id in state.ended_tool_call_ids: