add validation/warning for bettertransformers and torch version

src/axolotl/utils/validation.py

@@ -1,7 +1,7 @@
 """Module for validating config files"""
 
 import logging
-
+import torch
 
 def validate_config(cfg):
     if cfg.gradient_accumulation_steps and cfg.batch_size:
@@ -63,7 +63,10 @@ def validate_config(cfg):
         if cfg.fp16 or cfg.bf16:
             raise ValueError("AMP is not supported with BetterTransformer")
         if cfg.float16 is not True:
-            logging.warning("You should probably set float16 to true")
+            logging.warning("You should probably set float16 to true to load the model in float16 for BetterTransformers")
+        if torch.__version__.split(".")[0] < 2:
+            logging.warning("torch>=2.0.0 required")
+            raise ValueError(f"flash_optimum for BetterTransformers may not be used with {torch.__version__}")
 
     # TODO
     # MPT 7b