kstyle: expand tools area 1px downwards if present

Border shenanigans mean that the tools area is 1px less than it should be. Incrementing it fixes this.

BUG: 431540

kstyle/breezetoolsareamanager.cpp

@@ -63,6 +63,9 @@ namespace Breeze {
                 itemHeight = qMax(item->mapTo(window, item->rect().bottomLeft()).y(), itemHeight);
             }
         }
+        if (itemHeight > 0) {
+            itemHeight += window->devicePixelRatio();
+        }
 
         return QRect(0, 0, window->width(), itemHeight);
     }