FIX force_download in download utility (#4036)

FIX force_download in download utils

Author: Wauplin

src/diffusers/pipelines/pipeline_utils.py

@@ -1311,7 +1311,7 @@ def download(cls, pretrained_model_name, **kwargs) -> Union[str, os.PathLike]:
             snapshot_folder = Path(config_file).parent
             pipeline_is_cached = all((snapshot_folder / f).is_file() for f in expected_files)
 
-            if pipeline_is_cached:
+            if pipeline_is_cached and not force_download:
                 # if the pipeline is cached, we can directly return it
                 # else call snapshot_download
                 return snapshot_folder