apcupsd-service: create missing /run/apcupsd/ directory

apcupsd complains about this missing directory when it is starting the
shutdown procedure.

modules/services/monitoring/apcupsd.nix

@@ -150,6 +150,7 @@ in
  systemd.services.apcupsd = {
  description = "UPS daemon";
  wantedBy = [ "multi-user.target" ];
+ preStart = "mkdir -p /run/apcupsd/";
  serviceConfig = {
  ExecStart = "${pkgs.apcupsd}/bin/apcupsd -b -f ${configFile} -d1";
  };