You can send me email to lubos@manager.io and I’ll convert it for you. But all I do, I just import your data into the last version that has supported the old database format which is 20.9.89
And then send you back backup made in that version so it can be imported into the latest version.
SQLite has been added into Manager in late 2016. So this issue is affecting only users who didn’t upgrade for 5 years or longer.