Installing on ubuntu/pop_os 21.04 not possible yet through apt-get

When adding the repository source, i get an error after apt-get update

```
Reading package lists... Done
E: The repository 'http://ppa.launchpad.net/bablu-boy/nutty.0.1/ubuntu hirsute Release' does not have a Release file.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
```