fix: suppress DeprecationWarning in threaded uvicorn server

Python 3.14 deprecates asyncio.iscoroutinefunction(), which uvicorn
calls internally. With pytest's filterwarnings=['error'], this
DeprecationWarning becomes an exception that kills the server thread
before it can start listening.

In multiprocessing mode this was hidden because child processes don't
inherit pytest's warning filters. Threading shares the same process,
so we need to explicitly suppress DeprecationWarnings in the server
thread.

Author: perhapzz

tests/shared/test_streamable_http.py

@@ -11,6 +11,7 @@
 import threading
 import time
 import traceback
+import warnings
 from collections.abc import AsyncIterator, Generator
 from contextlib import asynccontextmanager
 from dataclasses import dataclass, field
@@ -1553,7 +1554,13 @@ def _create_context_aware_server(port: int) -> uvicorn.Server:
 def context_aware_server(basic_server_port: int) -> Generator[None, None, None]:
     """Start the context-aware server on a background thread (in-process for coverage)."""
     server_instance = _create_context_aware_server(basic_server_port)
-    thread = threading.Thread(target=server_instance.run, daemon=True)
+
+    def _run() -> None:
+        with warnings.catch_warnings():
+            warnings.filterwarnings("ignore", category=DeprecationWarning)
+            server_instance.run()
+
+    thread = threading.Thread(target=_run, daemon=True)
     thread.start()
 
     wait_for_server(basic_server_port)