Revert "Switch from i3-gaps to i3 due to merge"

This reverts commit 877533da92.

hosts/desktop.nix

@@ -22,7 +22,10 @@
         };
         defaultSession = "none+i3";
       };
-      windowManager.i3.enable = true;
+      windowManager.i3 = {
+        enable = true;
+        package = pkgs.i3-gaps;
+      };
     };
   };