[CI]Add version number.

[congw729]

PLEASE FILL IN THE PR DESCRIPTION HERE ENSURING ALL CHECKLIST ITEMS (AT THE BOTTOM) HAVE BEEN CONSIDERED.

Purpose

Add version number for vllm_omni.

Test Plan

Install the whl and check vllm_omni.__version__. Installation steps:

./scripts/build_wheel.sh --create-venv 
uv venv --python 3.12 --seed .venv-release-test
source .venv-release-test/bin/activate
uv pip install --reinstall "vllm==0.11.0" && uv pip install data/vllm_omni-<version>-py3-none-any.whl

Test Result

>> python -c "import vllm_omni; from vllm_omni import OmniLLM; vllm_omni.__version__”
INFO 11-27 15:46:08 [__init__.py:216] Automatically detected platform cuda.
'0.11.0rc1'

---

Essential Elements of an Effective PR Description Checklist

• The purpose of the PR, such as "Fix some issue (link existing issues this PR will resolve)".
• The test plan, such as providing test command.
• The test results, such as pasting the results comparison before and after, or e2e results
• (Optional) The necessary documentation update, such as updating supported_models.md and examples for a new model.
• (Optional) Release notes update. If your change is user facing, please update the release notes draft.

BEFORE SUBMITTING, PLEASE READ https://github.com/vllm-project/vllm-omni/blob/main/CONTRIBUTING.md (anything written below this line will be removed by GitHub Actions)

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[congw729]

Functioning as expected.

[Gaohan123]

lgtm, thanks!