fix typo

kamailio/presence_notify_sync-role.cfg

@@ -65,7 +65,7 @@ event_route[presence:notify-reply]
     $xavp(pres=>delete_subscription) = 0;
 
     if($notify_reply($rs) == 200) {
-       sht(notify=>$ci) = $null;
+       $sht(notify=>$ci) = $null;
        xlog("L_INFO", "$ci|end|notified $subs(watcher_username)@$subs(watcher_domain) on behalf of $subs(pres_uri)\n");
     } else if($notify_reply($rs) == 481 && $subs(reason) == "timeout") {
        xlog("L_INFO","$ci|end|sent subscription $hdr(Subscription-State)\n");