gnome3.tracker module: add self to systemd path

fixes GDBus.Error:org.freedesktop.systemd1.NoSuchUnit: Unit
tracker-store.service not found. - indexing for (null) will not work

Changed files
+2
nixos
modules
services
desktops
gnome3
+2
nixos/modules/services/desktops/gnome3/tracker.nix
···
services.dbus.packages = [ gnome3.tracker ];
+
systemd.packages = [ gnome3.tracker ];
+
};
}