Unexpected token when using more varaibles in <?= ?> php echo statement

• PHPMD version: 2.12.0
• PHP Version: 8.0, 8.1
• Installation type: composer, in docker image
• Operating System / Distribution & Version: Alpine, ubuntu 20.04

Current Behavior

Unexpected token: ,, line: 6, col: 10, file:: /test.php

Expected Behavior

Analysis should work

Steps To Reproduce:

• Install PHPMD composer require --dev phpmd/phpmd
• create test.php file with code example below
• run php vendor/bin/phpmd test.php ansi naming

Example code

<?php
$var1 = 'foo';
$var2 = 'bar';
?>

<?= $var1,$var2 ?>

Checks before submitting

• Be sure that there isn't already an issue about this. See: Issues list
• Be sure that there isn't already a pull request about this. See: Pull requests
• I have added every step to reproduce the bug.
• If possible I added relevant code examples.
• This issue is about 1 bug and nothing more.
• The issue has a descriptive title. For example: "JSON rendering failed on Windows for filenames with space".