Bug 25237: Fix semantic heading for opac-details

Bug 25237: Fix semantic heading for opac-details

Prior to this patch the opac-details view contained semantically incorrect h3
headings for the author information.

Test plan
1/ Perform a search in the OPAC that will yield results
2/ Navigate to any results detailed view
3/ Inspect the page and note that there are semantically incorrect headings
   H1 (Page title) > H2 (Item title) > H5 (Author)
4/ Apply the patch
5/ Reload the page
6/ Inspect the page and note that the semantically incorrect author block has
   been converted to a span with an 'h3' class for styling
7/ Note the page still appears nicely
8/ Signoff

Bonus points: Check with XSLT views enabled and disabled.

Signed-off-by: Sally <sally.healey@cheshiresharedservices.gov.uk>

Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>

Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>