WeChat uses fixed string for IMEI on Android 10

[Zhuoyun Wei]

According to this comment, WeChat uses the fixed string 1234567890ABCDEF in place of IMEI on Android 10 devices. I've verified this and the first 7 chars of md5('1234567890ABCDEF' + uin) is actually the real password of my EnMicroMsg.db.

Maybe we should document this in README, or even try this as a fallback method in the automatic script.

[Yuxin Wu]

thanks! now added