Fix ui build warning

Author: nyalldawson

src/ui/qgscredentialdialog.ui

@@ -185,7 +185,7 @@ font-style: italic;
          <property name="title">
           <string>Password attempts: #</string>
          </property>
-         <layout class="QVBoxLayout" name="verticalLayout_2">
+         <layout class="QVBoxLayout" name="verticalLayout_21">
           <property name="leftMargin">
            <number>6</number>
           </property>