Update DS Chat transformers req (deepspeedai#667)

This PR updates the transformers requirement in DS Chat to transformers>=4.31.0.

Author: lekurile

applications/DeepSpeed-Chat/requirements.txt

@@ -4,4 +4,4 @@ protobuf==3.20.3
 accelerate>=0.15.0
 torch>=1.12.0
 deepspeed>=0.9.0
-git+https://github.com/huggingface/transformers
+transformers>=4.31.0