Merge branch 'hotline/13648' into 'hotline_6.49'

Hotline #13648 Fix "ISO5426 to UTF8" conversion of '«' and '»'

This patch also replaces unimarc_archeo_animaux.txt by a valid ISO2709 file (yaz-marcdump was printing several errors about this file) and fix the corresponding unit tests

See merge request !322