It looks like this was introduced upstream in cups-filters (1.4.0-1). Here is what the changelog says:
cups-filters (1.4.0-1) unstable; urgency=medium
[...]
* Added dependencies on imagemagick (>= 6.4~), liblouisutdml-bin, and
poppler-utils to cups-filters, as they are needed to convert images, text,
and PDF to Braille, added antiword and docx2txt to Suggests: as they allow
converting Word files to Braille
It looks like this was introduced upstream in cups-filters (1.4.0-1). Here is what the changelog says:
cups-filters (1.4.0-1) unstable; urgency=medium
[...]
* Added dependencies on imagemagick (>= 6.4~), liblouisutdml-bin, and
poppler-utils to cups-filters, as they are needed to convert images, text,
and PDF to Braille, added antiword and docx2txt to Suggests: as they allow
converting Word files to Braille
-- Didier Raboud <email address hidden> Tue, 15 Dec 2015 11:04:23 +0100