[docs] add variant="fp16" flag (#4678)

docs/source/en/using-diffusers/inpaint.md

@@ -30,6 +30,7 @@ pipeline = StableDiffusionInpaintPipeline.from_pretrained(
     "runwayml/stable-diffusion-inpainting",
     torch_dtype=torch.float16,
     use_safetensors=True,
+    variant="fp16",
 )
 pipeline = pipeline.to("cuda")
 ```