[Feature]: Support Python 3.12

[zhuohan123]

🚀 The feature, motivation and pitch

I believe we eventually need to support 3.12 in the future. Right now I believe Pytorch just added support for Python 3.12, but ray still does not support Python 3.12. Let's use this issue to keep track on this.

Alternatives

No response

Additional context

No response

[pcmoritz]

Ray has been providing Python 3.12 wheels since 2.31.0 and since 2.33.0 we are running all the Ray Core tests on Python 3.12 (ray-project/ray#46650), so there is no reason to hold back upgrading :)

[seppd]

The project is not buildable from source with python 3.12:

% pip install -e .
...
INFO: pip is looking at multiple versions of vllm to determine which version is compatible with other requirements. This could take a while.
ERROR: Ignored the following versions that require a different python version: 1.21.2 Requires-Python >=3.7,<3.11; 1.21.3 Requires-Python >=3.7,<3.11; 1.21.4 Requires-Python >=3.7,<3.11; 1.21.5 Requires-Python >=3.7,<3.11; 1.21.6 Requires-Python >=3.7,<3.11
ERROR: Could not find a version that satisfies the requirement vllm-flash-attn==2.5.9.post1 (from vllm) (from versions: none)
ERROR: No matching distribution found for vllm-flash-attn==2.5.9.post1