fix for dropdown toggle icon

Author: Karlasa

app/design/frontend/Magento/blank/web/css/source/_extends.less

@@ -1401,7 +1401,7 @@
         &.active {
             > .title {
                 .lib-icon-font-symbol(
-                @_icon-font-content: @icon-prev,
+                @_icon-font-content: @icon-up,
                 @_icon-font-position: after
                 );
             }