vacation.pl: fix for https://sourceforge.net/tracker/?func=detail&atid=937964&aid=2040288&group_id=191583

git-svn-id: https://svn.code.sf.net/p/postfixadmin/code/trunk@442 a1433add-5e2c-0410-b055-b7f2511e0802

VIRTUAL_VACATION/vacation.pl

@@ -167,7 +167,7 @@ else {
         filename => $logfile,
         mode => 'append');
 
-    my $logger = get_logger();
+    $logger = get_logger();
     $appender->layout($log_layout);
     $logger->add_appender($appender);