increase AIOHTTP_TIMEOUT for long context test (vllm-project#226)

Author: yma11

benchmarks/backend_request_func.py

@@ -17,7 +17,7 @@
 # NOTE(simon): do not import vLLM here so the benchmark script
 # can run without vLLM installed.
 
-AIOHTTP_TIMEOUT = aiohttp.ClientTimeout(total=6 * 60 * 60)
+AIOHTTP_TIMEOUT = aiohttp.ClientTimeout(total=2 * 6 * 60 * 60)
 
 
 @dataclass