fix: load_image should support PIL Image (#6904)

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

src/diffusers/utils/loading_utils.py

@@ -32,6 +32,8 @@ def load_image(
             raise ValueError(
                 f"Incorrect path or URL. URLs must start with `http://` or `https://`, and {image} is not a valid path."
             )
+    elif isinstance(image, PIL.Image.Image):
+        image = image
     else:
         raise ValueError(
             "Incorrect format used for the image. Should be a URL linking to an image, a local path, or a PIL image."