Bug 28524: Escape 'rank' in cat_issues_top.pl

Bug 28524: Escape 'rank' in cat_issues_top.pl

It's a MySQL 8 keyword

Test plan:
Turn off strict_sql_modes (there are other problems in this script)
Hit Home Reports > Most-circulated items
Submit the form

Without this patch you got:
  You have an error in your SQL syntax; check the manual that
  corresponds to your MySQL server version for the right syntax to use
  near 'RANK, biblio.biblionumber AS ID, itemcallnumber as CALLNUM,
  ccode as CCODE, loca' at line 1

With this patch applied you see the report result view

Signed-off-by: Owen Leonard <oleonard@myacpl.org>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>