bugfix: updated scaling factor for SDXL

[lopez-hector]

Updating the scale factor for SDXL. Using the prior scale factor results in hazy images. Updated scale factor is from https://huggingface.co/stabilityai/stable-diffusion-xl-base-1.0/blob/main/vae/config.json

with updated scale factor (0.13025):

with prior scale factor (0.18215):

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[cchance27]

any chance this is getting merged soon?