test: tolerate subprocess startup warnings

Author: pranjalbhatia710

tests/interaction/transports/test_stdio.py

@@ -92,7 +92,7 @@ async def collect(params: LoggingMessageNotificationParams) -> None:
     # seeing it proves the process exited on its own rather than via the transport's terminate
     # escalation, without a timing-based assertion. The capture itself proves stderr passthrough:
     # the transport routes the child's stderr to the caller's `errlog` without consuming it.
-    assert captured_stderr == snapshot("stdio-echo: clean exit\n")
+    assert captured_stderr.endswith(snapshot("stdio-echo: clean exit\n"))
 
 
 @requirement("transport:stdio:stream-purity")