magento#21162: Fixed static tests

Author: sivaschenko

app/design/adminhtml/Magento/backend/web/css/source/forms/_temp.less

@@ -407,7 +407,7 @@ label.mage-error {
             padding: 0;
             width: 16px;
             z-index: 1;
-            
+
             &:before {
                 // @codingStandardsIgnoreStart
                 &:extend(.admin__control-checkbox + label:before);