nixos/uptime-kuma: add ping in path (#212001)

Co-authored-by: Sandro <[e-mail]>

nixos/modules/services/monitoring/uptime-kuma.nix

···
       after = [ "network.target" ];
       wantedBy = [ "multi-user.target" ];
       environment = cfg.settings;
-      path = lib.mkIf cfg.appriseSupport (with pkgs; [ apprise ]);
+      path = with pkgs; [ unixtools.ping ] ++ lib.optional cfg.appriseSupport apprise;
       serviceConfig = {
         Type = "simple";
         StateDirectory = "uptime-kuma";