Fix typos in the ValueError for a nested image list as StableDiffusionControlNetPipeline input. (#6286)

Fixed typos in the `ValueError` for a nested image list as input.

Author: celestialphineas

src/diffusers/pipelines/controlnet/pipeline_controlnet.py

@@ -633,7 +633,7 @@ def check_inputs(
             # When `image` is a nested list:
             # (e.g. [[canny_image_1, pose_image_1], [canny_image_2, pose_image_2]])
             elif any(isinstance(i, list) for i in image):
-                raise ValueError("A single batch of multiple conditionings are supported at the moment.")
+                raise ValueError("A single batch of multiple conditionings is not supported at the moment.")
             elif len(image) != len(self.controlnet.nets):
                 raise ValueError(
                     f"For multiple controlnets: `image` must have the same length as the number of controlnets, but got {len(image)} images and {len(self.controlnet.nets)} ControlNets."
@@ -659,7 +659,7 @@ def check_inputs(
         ):
             if isinstance(controlnet_conditioning_scale, list):
                 if any(isinstance(i, list) for i in controlnet_conditioning_scale):
-                    raise ValueError("A single batch of multiple conditionings are supported at the moment.")
+                    raise ValueError("A single batch of multiple conditionings is not supported at the moment.")
             elif isinstance(controlnet_conditioning_scale, list) and len(controlnet_conditioning_scale) != len(
                 self.controlnet.nets
             ):