flake: switch back entire config to unstable

Mixing stable and unstable brought me weird problems, so I'm switching
back to unstable entirely until it breaks hard enough to convince me to
go back to stable. :)

base/gui-programs.nix

@@ -3,20 +3,20 @@
   environment.systemPackages = with pkgs; [
     element-desktop
     feh
+    firefox
     gimp
     gnome.nautilus
     imagemagick
     mpv
     pavucontrol
+    slack
+    spotify
+    tdesktop
+    teams
     thunderbird
     zathura
 
     unstable.discord
-    unstable.firefox
-    unstable.slack
-    unstable.spotify
-    unstable.tdesktop
-    unstable.teams
   ];
 
   networking.networkmanager.enable = true;