Fix tabbedview breakpoint width (#12556)

Which should be 1024 according to the designs, not 768

Author: dbkr

res/css/structures/_TabbedView.pcss

@@ -167,7 +167,7 @@ limitations under the License.
 }
 
 /* Hide the labels on tabs, showing only the icons, on narrow viewports. */
-@media (max-width: 768px) {
+@media (max-width: 1024px) {
     .mx_TabbedView_tabsOnLeft.mx_TabbedView_responsive {
         .mx_TabbedView_tabLabel_text {
             display: none;