_is_peft_model update to recognise peft submodules, allowing training quantised models with peft submodules

src/transformers/trainer.py

@@ -247,7 +247,12 @@ def _is_peft_model(model):
             from peft import PeftMixedModel
 
             classes_to_check = (*classes_to_check, PeftMixedModel)
-        return isinstance(model, classes_to_check)
+        if isinstance(model, classes_to_check):
+            return True
+        else:
+            for submodule in model.modules():
+                if isinstance(submodule, classes_to_check):
+                    return True
     return False