sway: restore use of pkgs.sway

Using the final package in the `onChange` block broke some use cases.
This restores the old behavior and instead solves the test
dependencies in a different way.

Fixes #1611

This reverts commit 7c3c64208e.

modules/services/window-managers/i3-sway/sway.nix

@@ -399,7 +399,7 @@ in {
         swaySocket=''${XDG_RUNTIME_DIR:-/run/user/$UID}/sway-ipc.$UID.$(${pkgs.procps}/bin/pgrep -x sway || ${pkgs.coreutils}/bin/true).sock
         if [ -S $swaySocket ]; then
           echo "Reloading sway"
-          $DRY_RUN_CMD ${cfg.package}/bin/swaymsg -s $swaySocket reload
+          $DRY_RUN_CMD ${pkgs.sway}/bin/swaymsg -s $swaySocket reload
         fi
       '';
     };