Fix: Permission interface mismatch on flutter 3 broke compile

[maltemedocs]

See https://github.com/dev-juyoung/Fitness/issues/15

I just wanted to show a fix. I'm nor sure whether you would want to keep this backwards compatible, if that's possible.

[danielandricic]

This solution worked for me, but this is not a permanent solution. You would have to change it, every time, if you run flutter clean as I know.