[fix] simple theme: img tile, shows duplicate information on screen

Remove global title attribute from img tag[1][2] .  In the image result, the
title is already shown from span class title::

    <span class="title">{{ result.title|striptags }}</span>

See commit: 8fbffb14

    [fix] simple-theme templates: polish HTML <img> elements

[1] https://developer.mozilla.org/en-US/docs/Web/HTML/Element/img
[2] https://developer.mozilla.org/en-US/docs/Web/HTML/Global_attributes#attr-title

Reported-by: @dalf https://github.com/searxng/searxng/pull/545#issuecomment-980531215


Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>