fix: enhance error handling for invalid request types in relay handlers

common/gin.go

@@ -2,12 +2,13 @@ package common
 
 import (
 	"bytes"
-	"github.com/gin-gonic/gin"
 	"io"
 	"net/http"
 	"one-api/constant"
 	"strings"
 	"time"
+
+	"github.com/gin-gonic/gin"
 )
 
 const KeyRequestBody = "key_request_body"