fix typo in diffusion solver config

[hadyelsahar]

What?

This is probably an issue with the config file for the diffusion model. The generation sample rate should be added to the generate and not in dataset.generate

This generate.audio params are passed to audio_write functions save audio using ffmpeg in the following line

audiocraft/audiocraft/utils/samples/manager.py

Line 193 in 69fea8b

audio_path = audio_write(stem_path, wav, **self.xp.cfg.generate.audio)

Test

python3 -m pdb -c c -m  dora run solver=diffusion/encodec_24khz execute_only=generate continue_from=/path_to_ckpt.th dset=audio/default