[AudioLDM 2] Pipeline fixes (#4738)
* fix docs
* fix unet docs
* use image output for latents
* fix hub checkpoints
* fix pipeline example
* update example
* return_dict = False
* revert image pipeline output
* revert doc changes
* remove dtype test
* make style
* remove docstring updates
* remove unet docstring update
* Empty commit to re-trigger CI
* fix cpu offload
* fix dtype test
* add offload test
