STRING_AGG() fix for metabib.staged_browse()

We need to supply TEXT values to STRING_AGG(), so cast the input INTEGER
accordingly.

Also, I LIKE ALL-CAPS.

Signed-off-by: Dan Scott <dscott@laurentian.ca>
Signed-off-by: Ben Shum <bshum@biblio.org>
Stamping upgrade for STRING_AGG fix for metabib.staged_browse()

Signed-off-by: Ben Shum <bshum@biblio.org>