ncurses: silence `setterm` errors on exit
ncurses: silence `setterm` errors on exit

`setterm` can fail, in which case cava exits with something like:

> setterm: terminal rxvt-unicode-256color does not support --blank

This commit silences the potential error.

karlstav/cava,nikp123/cava,nikp123/cava,karlstav/cava