encode caption

Co-authored-by: forevermatt <forevermatt@users.noreply.github.com>

Author: hobbitronics

themes/material/default/selectidp-links.php

@@ -111,7 +111,7 @@ function clickedAnyway(idpName) {
                                 src="<?= empty($idp['logoURL']) ? 'default-logo.png'
                                                                 : $idp['logoURL'] ?>">
                         </div>
-                        <span class="mdl-color-text--grey-600 logo-caption" ><?= empty($idp['logoCaption']) ? '<br>': $idp['logoCaption'] ?> </span>
+                        <span class="mdl-color-text--grey-600 logo-caption" ><?= empty($idp['logoCaption']) ? '<br>': htmlentities($idp['logoCaption']) ?> </span>
                     </div>
                 </div>
             </div>