Fix object has no attribute 'flush' when using without a console (#8271)

fix

src/diffusers/utils/logging.py

@@ -82,6 +82,8 @@ def _configure_library_root_logger() -> None:
             # This library has already configured the library root logger.
             return
         _default_handler = logging.StreamHandler()  # Set sys.stderr as stream.
+
+        if sys.stderr:  # only if sys.stderr exists, e.g. when not using pythonw in windows
             _default_handler.flush = sys.stderr.flush
 
         # Apply our default configuration to the library root logger.