Remove trailing whitespace in forms.less

less/forms.less

@@ -144,7 +144,7 @@ output {
     background-color: @input-bg-disabled;
     opacity: 1; // iOS fix for unreadable disabled content; see https://github.com/twbs/bootstrap/issues/11655
   }
-  
+
   &[disabled],
   fieldset[disabled] & {
     cursor: @cursor-disabled;