Fix the Ghostscript normalization output format
Fix the Ghostscript normalization output format

Adds a migration to fix the Ghostscript normalization command "Command
Transcoding to pdfa with Ghostscript" so that it documents its true output
format as PDF/A 1b (fmt/354) and not PDF/A 1a (fmt/95).

Contributes to fixing https://github.com/artefactual/archivematica/issues/1158

artefactual/archivematica-fpr-admin,artefactual/archivematica-fpr-admin,artefactual/archivematica-fpr-admin,artefactual/archivematica-fpr-admin