fix: add explicit timeout to OpenAPI tool httpx client

src/google/adk/tools/openapi_tool/openapi_spec_parser/rest_api_tool.py

@@ -560,6 +560,7 @@ def __repr__(self):
 
 async def _request(**request_params) -> httpx.Response:
   async with httpx.AsyncClient(
-      verify=request_params.pop("verify", True)
+      verify=request_params.pop("verify", True),
+      timeout=request_params.pop("timeout", httpx.Timeout(600.0)),
   ) as client:
     return await client.request(**request_params)