Update scaling_factor for SDXL

Update `scaling_factor` to match SDXL repo https://github.com/Stability-AI/generative-models/blob/main/configs/inference/sd_xl_base.yaml#L4

config.json

@@ -21,7 +21,7 @@
   "norm_num_groups": 32,
   "out_channels": 3,
   "sample_size": 512,
-  "scaling_factor": 0.18215,
+  "scaling_factor": 0.13025,
   "up_block_types": [
     "UpDecoderBlock2D",
     "UpDecoderBlock2D",