Bug 34015: Terminology: Relative issues should be Relative's checkouts

This patch changes the term 'issues' in a screen reader caption in the
OPAC to the correct term 'checkouts'.

To test:
Setup:
- Have a patron with a guarantee
- Check out an item to the guarantee
- Make sure the guarantee allows their guarantor to see their checkouts
  (AllowStaffToSetCheckoutsVisibilityForGuarantor must be on for you to
  be able to set this)

1. In the OPAC, log in with the guarantor patron
2. Click on the Relatives' checkouts tab
3. Open a screen reader (in Ubuntu, Super + Alt + S to turn on/off)
4. Navigate to the table in the Relative's checkouts tab
   --> The screen reader should say 'Relative issue table with...'
5. Apply patch
6. Refresh the page
7. Restart the screen reader (if it was off)
   --> The screen reader should now say 'Relatives' checkouts table
   with...'

Alternatively, open the page inspector and inspect the table, the
caption is in the table tag, before the thead tag.

Signed-off-by: Owen Leonard <oleonard@myacpl.org>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>

koha-tmpl/opac-tmpl/bootstrap/en/modules/opac-user.tt

@@ -667,7 +667,7 @@
                             [% IF relatives %]
                                 <div id="opac-user-relative-issues" class="tab-pane" role="tabpanel" aria-labelledby="opac-user-relative-issues-tab">
                                     <table id="opac-user-relative-issues-table" class="table table-bordered table-striped">
-                                        <caption class="sr-only">Relative issues</caption>
+                                        <caption class="sr-only">Relatives' checkouts</caption>
                                         <thead>
                                             <tr>
                                                 <th class="anti-the">Title</th>