fix(接口定义): 修复接口定义case列表，点击编辑查看变更记录查看详情报错的缺陷

--bug=1010573 --user=王孝刚 【接口测试】-接口定义-case列表，点击编辑查看 变更记录，点击查看详情报错
https://www.tapd.cn/55049933/s/1109146

frontend/src/business/components/history/HistoryDetail.vue

@@ -39,8 +39,8 @@
     methods: {
       getDiff(v1, v2) {
         if (this.detail.columnName==='request' && v1 && v2){
-          let delta = jsondiffpatch.diff(JSON.parse(v1) , JSON.parse(v2));
-          return formattersHtml.format(delta, JSON.parse(v1));
+          let delta = jsondiffpatch.diff(JSON.parse(JSON.stringify(v1)), JSON.parse(JSON.stringify(v2)));
+          return formattersHtml.format(delta, JSON.parse(JSON.stringify(v1)));
         }
         let delta = jsondiffpatch.diff(v1 , v2);
         return formattersHtml.format(delta, v1);