Bug 32734: (QA follow-up) Make use of $c->objects->to_api

Bug 32734: (QA follow-up) Make use of $c->objects->to_api

This is using plain `$biblios->to_api` but as of bug 33080, the new
helper should be used instead. This patch fixes that.

To test:
1. Run:
   $ ktd --shell
  k$ prove t/db_dependent/api/v1/biblios.t
=> SUCCESS: Tests pass!
2. Apply this patch
3. Repeat 1
=> SUCCESS: Tests pass!

Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
(cherry picked from commit a8daacac2c0e80c70d3665a2016cbb20b16bcf5e)
Signed-off-by: Matt Blenkinsop <matt.blenkinsop@ptfs-europe.com>