Pin Ray version to 2.40.0

[WoosukKwon]

It turns out that TP + PP in V1 does not work with Ray 2.41.0 for some reason. 2.40.0 works though.

Just for a record, I got the following error on 2.41.0:

EngineCore hit an exception: Traceback (most recent call last):
ERROR 02-18 01:08:08 core.py:283]   File "/data/woosuk/workspace/vllm/vllm/v1/engine/core.py", line 276, in run_engine_core
ERROR 02-18 01:08:08 core.py:283]     engine_core.run_busy_loop()
ERROR 02-18 01:08:08 core.py:283]   File "/data/woosuk/workspace/vllm/vllm/v1/engine/core.py", line 319, in run_busy_loop
ERROR 02-18 01:08:08 core.py:283]     outputs = step_fn()
ERROR 02-18 01:08:08 core.py:283]               ^^^^^^^^^
ERROR 02-18 01:08:08 core.py:283]   File "/data/woosuk/workspace/vllm/vllm/v1/engine/core.py", line 193, in step_with_batch_queue
ERROR 02-18 01:08:08 core.py:283]     model_output = future.result()
ERROR 02-18 01:08:08 core.py:283]                    ^^^^^^^^^^^^^^^
ERROR 02-18 01:08:08 core.py:283]   File "/data/woosuk/workspace/vllm/vllm/v1/executor/ray_distributed_executor.py", line 24, in result
ERROR 02-18 01:08:08 core.py:283]     return self.ref.get()
ERROR 02-18 01:08:08 core.py:283]            ^^^^^^^^^^^^^^
ERROR 02-18 01:08:08 core.py:283]   File "/data/woosuk/miniconda3/envs/vllm-py311/lib/python3.11/site-packages/ray/experimental/compiled_dag_ref.py", line 115, in get
ERROR 02-18 01:08:08 core.py:283]     return_vals = self._dag._execute_until(
ERROR 02-18 01:08:08 core.py:283]                   ^^^^^^^^^^^^^^^^^^^^^^^^^
ERROR 02-18 01:08:08 core.py:283]   File "/data/woosuk/miniconda3/envs/vllm-py311/lib/python3.11/site-packages/ray/dag/compiled_dag_node.py", line 2074, in _execute_until
ERROR 02-18 01:08:08 core.py:283]     return self._get_execution_results(execution_index, channel_index)
ERROR 02-18 01:08:08 core.py:283]            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
ERROR 02-18 01:08:08 core.py:283]   File "/data/woosuk/miniconda3/envs/vllm-py311/lib/python3.11/site-packages/ray/dag/compiled_dag_node.py", line 1982, in _get_execution_results
ERROR 02-18 01:08:08 core.py:283]     assert execution_index in self._result_buffer
ERROR 02-18 01:08:08 core.py:283]            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
ERROR 02-18 01:08:08 core.py:283] AssertionError

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[anrooo]

Hey, did you have any additional context here? We're getting blocked on this incompatibility as we needed some of the other bug fixes in Ray 2.41 and looking for a solution.

[comaniac]

This PR is merged: #13994