[InterNetNews/inn] de8608: Another signedness to fix

[Julien ÉLIE]

  Branch: refs/heads/main
  Home:   https://github.com/InterNetNews/inn
  Commit: de86086adee7bf51f9731b29a6d37c5010128246
      https://github.com/InterNetNews/inn/commit/de86086adee7bf51f9731b29a6d37c5010128246
  Author: Julien ÉLIE <Julien-Elie at users.noreply.github.com>
  Date:   2024-02-11 (Sun, 11 Feb 2024)

  Changed paths:
    M backends/ninpaths.c

  Log Message:
  -----------
  Another signedness to fix

With -Wformat-signedness GCC warning.