nixos/usbguard: Do not check permissions on rules file (using undocumented -P flag)

nixos/modules/services/security/usbguard.nix

···
 
       serviceConfig = {
         Type = "simple";
-        ExecStart = ''${pkgs.usbguard}/bin/usbguard-daemon -d -k -c ${daemonConfFile}'';
+        ExecStart = ''${pkgs.usbguard}/bin/usbguard-daemon -P -d -k -c ${daemonConfFile}'';
         Restart = "on-failure";
       };
     };