nixos/deconz: treat SIGTERM exit status as success

deconz doesn't handle SIGTERM and terminates with code 143 (128 + 15
(SIGTERM) instead of 0. This results in systemd marking the service as
failed when a user stops it (with `systemctl stop deconz`). Fix it by
treating code 143 as success.

nixos/modules/services/networking/deconz.nix

@@ -122,6 +122,7 @@ in
         RuntimeDirectory = name;
         RuntimeDirectoryMode = "0700";
         StateDirectory = name;
+        SuccessExitStatus = [ 143 ];
         WorkingDirectory = stateDir;
         # For access to /dev/ttyACM0 (ConBee).
         SupplementaryGroups = [ "dialout" ];