Merge pull request #231266 from teto/swaync-mainProgram

swaynotificationcenter: set meta.mainProgram

pkgs/applications/misc/swaynotificationcenter/default.nix

···
     changelog = "https://github.com/ErikReider/SwayNotificationCenter/releases/tag/v${version}";
     license = licenses.gpl3;
     platforms = platforms.linux;
+    mainProgram = "swaync";
     maintainers = with maintainers; [ berbiche pedrohlc ];
   };
 })