Update pipeline.py

When use example like "prompt =Image.open.(path/to/*.png)", the type is class( Image.Image), check_inputs will raise ValueError...

pipeline.py

@@ -414,7 +414,7 @@ class MatForgerPipeline(DiffusionPipeline, FromSingleFileMixin):
                 "Provide either `prompt` or `prompt_embeds`. Cannot leave both `prompt` and `prompt_embeds` undefined."
             )
         elif prompt is not None and (
-            not isinstance(prompt, str) and not isinstance(prompt, list)
+            not isinstance(prompt, str) and not isinstance(prompt, list) or not isinstance(prompt, Image.Image)
         ):
             raise ValueError(
                 f"`prompt` has to be of type `str` or `list` but is {type(prompt)}"