Add spacer between widget and dialogbox button

So layout is ok when we resize this dialogbox

Change-Id: I1b6bec39547808795ae9e516f6a4aaa20d892b35
Reviewed-by: Orgad Shaneh <orgads@gmail.com>

src/plugins/git/branchadddialog.ui

@@ -31,7 +31,7 @@
      </property>
     </widget>
    </item>
-   <item row="2" column="0" colspan="2">
+   <item row="3" column="0" colspan="2">
     <widget class="QDialogButtonBox" name="buttonBox">
      <property name="orientation">
       <enum>Qt::Horizontal</enum>
@@ -41,6 +41,19 @@
      </property>
     </widget>
    </item>
+   <item row="2" column="0" colspan="2">
+    <spacer name="verticalSpacer">
+     <property name="orientation">
+      <enum>Qt::Vertical</enum>
+     </property>
+     <property name="sizeHint" stdset="0">
+      <size>
+       <width>20</width>
+       <height>40</height>
+      </size>
+     </property>
+    </spacer>
+   </item>
   </layout>
  </widget>
  <resources/>