oops: Fix bad HTML entity #2

Follow-up PR to the comment here:
https://github.com/osTicket/osTicket-1.8/commit/06d3a0f3e2a4557ca72faa916859b9315635dfe4

include/staff/filter.inc.php

@@ -142,7 +142,7 @@ $info=Format::htmlchars(($errors && $_POST)?$_POST:$info);
                         <?php } ?>
                     </select>
                     <select name="rule_h<?php echo $i; ?>">
-                        <option value="0">&mdash; <?php echo __('Select One');?> &dash;</option>
+                        <option value="0">&mdash; <?php echo __('Select One');?> &mdash;</option>
                         <?php
                         foreach($match_types as $k=>$v){
                             $sel=($info["rule_h$i"]==$k)?'selected="selected"':'';