fix(avatar): add default cache max age for avatar response

service/user/setting.go

@@ -76,6 +76,8 @@ type ThemeChose struct {
 	Theme string `json:"theme" binding:"required,hexcolor|rgb|rgba|hsl"`
 }
 
+const avatarMaxAge = 3600
+
 // Update 更新主题设定
 func (service *ThemeChose) Update(c *gin.Context, user *model.User) serializer.Response {
 	user.OptionsSerialized.PreferredTheme = service.Theme
@@ -194,6 +196,8 @@ func (service *AvatarService) Get(c *gin.Context) serializer.Response {
 		"l": model.GetSettingByName("avatar_size_l"),
 	}
 
+	c.Header("Cache-Control", fmt.Sprintf("max-age=%d", avatarMaxAge))
+
 	// Gravatar 头像重定向
 	if user.Avatar == "gravatar" {
 		server := model.GetSettingByName("gravatar_server")