Bug 22949: Markup error in OPAC course reserves template

Bug 22949: Markup error in OPAC course reserves template

This patch adds a missing "=" in opac-course-reserves.tt in order to
quiet errors returned by the HTML validator.

To reproduce the problem you should have one or more course reserves
available in the OPAC. Go to the course reserves page. Run the page
through the W3C validation service: https://validator.w3.org. Either by
pasting in the URL for the search results (if web accessible) or by
viewing source, copying, and pasting into "Validate by Direct Input."

This patch addresses these errors:

 - 'Quote " in attribute name. Probable cause: Matching quote missing
    somewhere earlier.'
 - 'Attribute class"inst_surname" not allowed on element span at this
    point.'

To test, apply the patch and try again to reproduce the validation
errors. Those errors should no longer be present. There should be no
visible change to the page.

Signed-off-by: Frederik Chenier <frederik@inlibro.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
(cherry picked from commit 35fe9cf40bb1472799db0f7596d33f1bd184fb9b)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>