fix inference in custom diffusion (#5329)

* Update train_custom_diffusion.py

* make style

* Empty-Commit

---------
Co-authored-by: Sayak Paul <spsayakpaul@gmail.com>

examples/custom_diffusion/train_custom_diffusion.py

@@ -1238,7 +1238,9 @@ def main(args):
                     # run inference
                     generator = torch.Generator(device=accelerator.device).manual_seed(args.seed)
                     images = [
-                    pipeline(args.validation_prompt, num_inference_steps=25, generator=generator, eta=1.0).images[0]
+                        pipeline(args.validation_prompt, num_inference_steps=25, generator=generator, eta=1.0).images[
+                            0
+                        ]
                         for _ in range(args.num_validation_images)
                     ]