:bug: fix select2 分组单选框 会默认选择第一个值

resources/views/form/select.blade.php

@@ -12,6 +12,7 @@
         <input type="hidden" name="{{$name}}"/>
 
         <select class="form-control {{$class}}" style="width: 100%;" name="{{$name}}" {!! $attributes !!} >
+            <option value=""></option>
             @if($groups)
                 @foreach($groups as $group)
                     <optgroup label="{{ $group['label'] }}">
@@ -21,7 +22,6 @@
                     </optgroup>
                 @endforeach
              @else
-                <option value=""></option>
                 @foreach($options as $select => $option)
                     <option value="{{$select}}" {{ Dcat\Admin\Support\Helper::equal($select, old($column, $value)) ?'selected':'' }}>{{$option}}</option>
                 @endforeach