refactor: use __future__.annotations

Author: Kludex

src/mcp/shared/session.py

@@ -206,7 +206,7 @@ def add_response_router(self, router: ResponseRouter) -> None:
         response stream mechanism. This is used by TaskResultHandler to route
         responses for queued task requests back to their resolvers.
 
-        !!! warn
+        !!! warning
             This is an experimental API that may change without notice.
 
         Args: