freshrss: use an absolute path for ExecStart

this fixes the issue after a recent PR on this file:
<https://github.com/NixOS/nixpkgs/pull/196140#discussion_r1002907603>

colin e4235c60 08d86733

Changed files
+1 -1
nixos
modules
services
web-apps
+1 -1
nixos/modules/services/web-apps/freshrss.nix
···
Group = "freshrss";
StateDirectory = "freshrss";
WorkingDirectory = cfg.package;
-
ExecStart = "./app/actualize_script.php";
+
ExecStart = "${cfg.package}/app/actualize_script.php";
} // systemd-hardening;
};
};