fix openai version to 0.28.1

install.sh

@@ -3,7 +3,7 @@ conda activate llmtime
 pip install numpy
 pip install -U jax[cpu] # we don't need GPU for jax
 pip install torch --index-url https://download.pytorch.org/whl/cu118
-pip install openai 
+pip install openai==0.28.1
 pip install tiktoken
 pip install tqdm
 pip install matplotlib