Add workflow to cancel running workflows on PR close

[pacoxu]

https://github.com/vllm-project/vllm-ascend/actions/runs/20735955959/job/59533181655 is still running after #5612 is closed.

And the action will be running for more than 2 hours, which needs to be cleanup.

It seems that the Github Aciton will not cancel it automatically, so I add this to cannel those PR related actions once it is closed.

• vLLM version: v0.13.0
• vLLM main: vllm-project/vllm@8be6432

[gemini-code-assist]

Note

Gemini is unable to generate a review for this pull request due to the file types involved not being currently supported.

[github-actions]

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