Add more save strategies for DPO training. (axolotl-ai-cloud#1255)

* Set save_strategy and save_steps in HFDPOTrainerBuilder

* fix doublicate save_steps

src/axolotl/core/trainer_builder.py

@@ -1096,13 +1096,21 @@ def build_training_arguments(self, total_num_steps):
                     "use_reentrant": False
                 }
 
+        # set save_strategy and save_steps
+        if self.cfg.save_steps:
+            training_args_kwargs["save_strategy"] = "steps"
+            training_args_kwargs["save_steps"] = self.cfg.save_steps
+        elif self.cfg.save_strategy:
+            training_args_kwargs["save_strategy"] = self.cfg.save_strategy
+        else:
+            # default to saving each epoch if not defined
+            training_args_kwargs["save_strategy"] = "epoch"
+
         training_args = TrainingArguments(
             per_device_train_batch_size=self.cfg.micro_batch_size,
             max_steps=self.cfg.max_steps or total_num_steps,
             gradient_accumulation_steps=self.cfg.gradient_accumulation_steps,
             learning_rate=self.cfg.learning_rate,
-            save_strategy="steps",
-            save_steps=self.cfg.save_steps,
             output_dir=self.cfg.output_dir,
             warmup_steps=self.cfg.warmup_steps,
             logging_first_step=True,