Be explicit with openai response choices limit (n parameter)

pkg/cli/openai.go

@@ -22,6 +22,7 @@ func CreateChatCompletionRequest(model string, messages []Message, maxTokens int
 		Model:     model,
 		Messages:  chatCompletionMessages,
 		MaxTokens: maxTokens,
+		N:         1, // limit responses to 1 "choice". we use choices[0] to reference it
 	}
 }