fix: gemini func call

constant/finish_reason.go

@@ -1,6 +1,9 @@
 package constant
 
 var (
-	FinishReasonStop      = "stop"
-	FinishReasonToolCalls = "tool_calls"
+	FinishReasonStop          = "stop"
+	FinishReasonToolCalls     = "tool_calls"
+	FinishReasonLength        = "length"
+	FinishReasonFunctionCall  = "function_call"
+	FinishReasonContentFilter = "content_filter"
 )