Add `scale_factor` to vae config.

Hey flax 👋,

Your model repository seems to contain a stable diffusion checkpoint. We have just merged a [PR](https://github.com/huggingface/diffusers/pull/1860) in `diffusers` which makes `scaling_factor` (the magic 0.18215 number a config attribute of `vae`).

We strongly recommend that you merge this PR to make sure your model keeps working correctly with diffusers.

Diffusingly,
Suraj.

vae/config.json

@@ -20,6 +20,7 @@
   "norm_num_groups": 32,
   "out_channels": 3,
   "sample_size": 256,
+  "scaling_factor": 0.18215,
   "up_block_types": [
     "UpDecoderBlock2D",
     "UpDecoderBlock2D",