Update libpipeline to version 1.5.5 / rev 13 via SR 945521
    
    https://build.opensuse.org/request/show/945521
    by user WernerFink + dimstar_suse
    - Update to 1.5.5:
      * Move release process to GitLab CI.
    - Back to download from savannah.nongnu.org for a fully bootstrapped
      tar ball without the need of autoconfig and gl
      Compare https://gitlab.com/cjwatson/libpipeline/-/releases
      and     https://gitlab.com/cjwatson/libpipeline/-/packages/4425007
    
    - Use autoconf
    
    - update to 1.5.4:
      * Building libpipeline now requires Autoconf >= 2.64.
      * Developmed moved to Gitlab