BibFormat: larger column `format.code`

* Increases length of column 'format.code' to enable larger values.
  e.g. `recjson` (addresses #2072)

Signed-off-by: Eirini Psallida <eirini.psallida@cern.ch>
Reviewed-by: Jiri Kuncar <jiri.kuncar@cern.ch>