fix: update music search keyword and test case ID

- Changed the default search keyword in the API documentation from "这么可爱真是抱歉" to "妖精小姐的魔法邀约".
- Updated the test case for fetching song URL to use the correct song ID (from 1969519579 to 2756058128).

test/music_url.test.js

@@ -4,7 +4,7 @@ const host = global.host || 'http://localhost:3000'
 describe('测试获取歌曲是否正常', () => {
   it('歌曲的 url 不应该为空', (done) => {
     const qs = {
-      id: 1969519579,
+      id: 2756058128,
       br: 999000,
       realIP: global.cnIp,
     }