feat: add support for gpt-3.5-turbo-instruct (close #545)

common/model-ratio.go

@@ -24,6 +24,7 @@ var ModelRatio = map[string]float64{
 	"gpt-3.5-turbo-0613":        0.75,
 	"gpt-3.5-turbo-16k":         1.5, // $0.003 / 1K tokens
 	"gpt-3.5-turbo-16k-0613":    1.5,
+	"gpt-3.5-turbo-instruct":    0.75, // $0.0015 / 1K tokens
 	"text-ada-001":              0.2,
 	"text-babbage-001":          0.25,
 	"text-curie-001":            1,