Disables check for packing by the te_helper util since not all dataset

configs use packing (CV/Multimodal)

t5x/te_helper.py

@@ -179,6 +179,8 @@ def update_fp8_metas(grad_accum, flax_mutables):
 
   @staticmethod
   def check_dataset_cfg(config):
+    if not hasattr(config, 'pack'):
+        return
     assert not config.pack, \
         "Transformer Engine does not support dataset.packing, please turn it off."