iso_gnome: Fix evaluation

`qt.enable` option requires `qt.style` to be set.
Previously, this was set in GNOME module but it has been removed
in 622745942bc7b7cc056bfbb0bc6004dd823fa4f5

-6
-6
nixos/modules/installer/cd-dvd/installation-cd-graphical-calamares-gnome.nix
··· 30 30 enable = true; 31 31 }; 32 32 33 - # Theme calamares with GNOME theme 34 - qt = { 35 - enable = true; 36 - platformTheme = "gnome"; 37 - }; 38 - 39 33 # Fix scaling for calamares on wayland 40 34 environment.variables = { 41 35 QT_QPA_PLATFORM = "$([[ $XDG_SESSION_TYPE = \"wayland\" ]] && echo \"wayland\")";