[Refactor] Remove resampy dependency

[Isotr0py]

Purpose

Actually, pyav performs audio resample much better than resampy, so there is not necessary to align with librosa's original implementation:
https://github.com/librosa/librosa/blob/e403272fc984bc4aeb316e5f15899042224bb9fe/librosa/core/audio.py#L637-L678

Performance Benchmark

Method	Mean (ms)	Median (ms)	Std (ms)	Min (ms)	Max (ms)
pyav	10.847	10.870	0.444	10.247	11.578
resampy	443.071	444.638	8.233	428.089	458.172

Quality Metrics (vs soxr reference)

Method	RMSE	MAE	SNR (dB)	Correlation	Aliasing	Spectral Conv.
pyav	0.03880904	0.00805858	+23.7606	0.99789495	0.27869838	0.06436387
resampy	0.06202365	0.00902251	+19.6881	0.99463281	0.26626801	0.10365593

Test Plan

pytest -s -v tests/entrypoints/openai/correctness/test_transcription_api_correctness.py

Test Result

Correctness tests still pass after using pyav resampler.

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[gemini-code-assist]

Code Review

This pull request removes the resampy dependency across the project, updating requirement files, setup.py, and audio processing modules. The default resampling method is transitioned to pyav. Feedback indicates that hardcoding resample_audio_pyav in load_audio_soundfile may cause runtime errors if the av package is missing, suggesting the use of AudioResampler or a fallback to scipy instead.

[gemini-code-assist]

In load_audio_soundfile, the resampling logic now hardcodes resample_audio_pyav. If the av package is not installed (e.g., if the user didn't install vllm[audio]), this will raise an error from the PlaceholderModule when resampling is required. It might be safer to use the AudioResampler class or provide a fallback to scipy if av is unavailable, especially since load_audio is a general utility.

[mergify]

This pull request has merge conflicts that must be resolved before it can be
merged. Please rebase the PR, @Isotr0py.

https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/working-with-forks/syncing-a-fork

[mergify]

This pull request has merge conflicts that must be resolved before it can be
merged. Please rebase the PR, @Isotr0py.

https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/working-with-forks/syncing-a-fork

[mergify]

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