feat: added function call info to chat completions (#390)

chat_stream.go

@@ -10,6 +10,7 @@ import (
 type ChatCompletionStreamChoiceDelta struct {
 	Content      string        `json:"content,omitempty"`
 	Role         string        `json:"role,omitempty"`
+	FunctionCall *FunctionCall `json:"function_call,omitempty"`
 }
 
 type ChatCompletionStreamChoice struct {