Removing vestigial mistral reward model converter references (#1307)

Author: SalmanMohammadi

torchtune/models/mistral/__init__.py

@@ -29,8 +29,6 @@
     "lora_mistral_classifier",
     "mistral",
     "mistral_classifier",
-    "mistral_reward_hf_to_tune",
-    "mistral_reward_tune_to_hf",
     "lora_mistral_7b",
     "lora_mistral_reward_7b",
     "mistral_7b",