[Refactor] Remove resampy dependency

[NickCao]

Purpose

Follows vllm-project/vllm#39524

Test Plan

TBD

Test Result

TBD

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• The purpose of the PR, such as "Fix some issue (link existing issues this PR will resolve)".
• The test plan. Please provide the test scripts & test commands. Please state the reasons if your codes don't require additional test scripts. For test file guidelines, please check the test style doc
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[NickCao]

cc @Isotr0py

[hsliuustc0106]

BLOCKER scan:

• Correctness: PASS (API replacement looks correct)
• Reliability/Safety: PASS
• Breaking Changes: Needs clarification - is removing resampy from requirements/common.txt a user-facing change?
• Test Coverage: ISSUE - Test plan is TBD. Need to verify audio resampling works correctly with AudioResampler
• Documentation: ISSUE - No documentation update about the dependency removal
• Security: PASS

BLOCKING ISSUES:

1. Test Coverage - Missing test plan and results. Please verify that audio resampling produces the same output with AudioResampler as with resampy
2. Documentation - Should document the dependency removal and any migration steps if users were using resampy directly
3. Performance consideration - Creating a new AudioResampler instance each time (in loops) may be less efficient than the stateless resample_audio_resampy. Consider if this needs to be optimized

VERDICT: REQUEST_CHANGES

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Note: Since this is removing a dependency, please also verify that AudioResampler is available in the minimum supported vLLM version.