Update generation_utils.py

The `validate` method in `DreamGenerationConfig` misses a argument in base class `‎GenerationConfig`.
cf. https://huggingface.co/docs/transformers/en/main_classes/text_generation#transformers.GenerationConfig.validate

generation_utils.py

@@ -143,7 +143,7 @@ class DreamGenerationConfig(GenerationConfig):
         # Validate the values of the attributes
         self.validate(is_init=True)
 
-    def validate(self, is_init=False):
+    def validate(self, is_init=False, strict=False):
         pass
 
 class DreamGenerationMixin: