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>

Koha/REST/V1/Biblios.pm

@@ -619,7 +619,7 @@ sub list {
         if ( $c->req->headers->accept =~ m/application\/json(;.*)?$/ ) {
             return $c->render(
                 status => 200,
-                json   => $biblios->to_api
+                json   => $c->objects->to_api( $biblios ),
             );
         }
         elsif (