if we were to request Go>=1.15, we could use `embed.FS` to pack the files under `migrations` and have a fully relocatable `gpodder2go` binary. we would have to use [v4/source/iofs](https://pkg.go.dev/github.com/golang-migrate/migrate/v4@v4.15.2/source/iofs) instead of [v4/source/file](https://pkg.go.dev/github.com/golang-migrate/migrate/v4@v4.15.2/source/file) in `cmd/init.go`. WDYT ?