TypeError: mel() takes 0 positional arguments but 2 positional arguments (and 3 keyword-only arguments) were given

In recent librosa (0.10+), librosa.filters.mel made its parameters keyword-only. Wav2Lip’s audio.py still calls it with positional args:

passing keyword args:
```python
# audio.py
def _build_mel_basis():
    return librosa.filters.mel(
        sr=hp.sample_rate,
        n_fft=hp.n_fft,
        n_mels=hp.num_mels,
        fmin=hp.fmin,
        fmax=hp.fmax,
    )
``` 