Fix type annotations on StableDiffusionPipeline.__call__ (#682)

Fixed type annotations on StableDiffusionPipeline::__call__

src/diffusers/pipelines/stable_diffusion/pipeline_stable_diffusion.py

@@ -113,11 +113,11 @@ class StableDiffusionPipeline(DiffusionPipeline):
     def __call__(
         self,
         prompt: Union[str, List[str]],
-        height: Optional[int] = 512,
-        width: Optional[int] = 512,
-        num_inference_steps: Optional[int] = 50,
-        guidance_scale: Optional[float] = 7.5,
-        eta: Optional[float] = 0.0,
+        height: int = 512,
+        width: int = 512,
+        num_inference_steps: int = 50,
+        guidance_scale: float = 7.5,
+        eta: float = 0.0,
         generator: Optional[torch.Generator] = None,
         latents: Optional[torch.FloatTensor] = None,
         output_type: Optional[str] = "pil",