Pruning Size Buffer to prevent errors

[JoseMoranUrena523]

I'm still using Umbrel 0.5.4, and I got an error trying to launch Umbrel: Cannot read property of undefined (reading "status"). After some investigation, I found out that it's caused by the storage limit being reached. To fix this, I suggest that the maximum amount of GB you can set for pruning should be limited to the available space minus 20 GB (safe spot for app data and settings, unless you can get the exact amount of GB being used for app data and settings).