Update README.md

We need to import torch.

README.md

@@ -34,6 +34,7 @@ The model can be loaded with it's base pipeline `segmind/SSD-1B`. Next, the sche
 
 ```python
 from diffusers import UNet2DConditionModel, DiffusionPipeline, LCMScheduler
+import torch
 
 unet = UNet2DConditionModel.from_pretrained("latent-consistency/lcm-ssd-1b", torch_dtype=torch.float16, variant="fp16")
 pipe = DiffusionPipeline.from_pretrained("segmind/SSD-1B", unet=unet, torch_dtype=torch.float16, variant="fp16")