added z-index in cookie-policy

Fixes: https://code.ubuntu-it.org/ubuntu-it-web/www/-/issues/9

assets/scss/www.scss

@@ -170,3 +170,7 @@ div.page div.row div.col.image-attach-corner {
         }
     }
 }
+
+div.cookie-policy {
+    z-index: 10;
+}