Update menu.go (#271)

* Update menu.go

json: cannot unmarshal string into Go struct field MatchRule.conditionalmenu.matchrule.group_id of type int32
接口返回是字符串
"matchrule": {
"group_id": "2"
}

结构体定义
//MatchRule 个性化菜单规则
type MatchRule struct {
GroupID int32 json:"group_id,omitempty"
...
}

* matchrule字段均是字符串

 "matchrule": {
        "tag_id": "2", 
        "sex": "1", 
        "country": "中国", 
        "province": "广东", 
        "city": "广州", 
        "client_platform_type": "2", 
        "language": "zh_CN"
    }

officialaccount/menu/menu.go

@@ -102,12 +102,12 @@ type ButtonNew struct {
 
 //MatchRule 个性化菜单规则
 type MatchRule struct {
-	GroupID            int32  `json:"group_id,omitempty"`
-	Sex                int32  `json:"sex,omitempty"`
+	GroupID            string  `json:"group_id,omitempty"`
+	Sex                string  `json:"sex,omitempty"`
 	Country            string `json:"country,omitempty"`
 	Province           string `json:"province,omitempty"`
 	City               string `json:"city,omitempty"`
-	ClientPlatformType int32  `json:"client_platform_type,omitempty"`
+	ClientPlatformType string  `json:"client_platform_type,omitempty"`
 	Language           string `json:"language,omitempty"`
 }