Solve the PHP_CodeSniffer & PHP-Parser collision during Coverage Collection

[aik099]

• The PHPUnit 9.x started to use PHP-Parser during a coverage collection
• PHP-Parser expects T_* tokens from newer PHP versions used on the older PHP versions to have integer values: https://github.com/nikic/PHP-Parser/blob/master/lib/PhpParser/compatibility_tokens.php
• PHP_CodeSniffer also defines T_* tokens, but with string values
• coverage collection fails with Token T_NAME_QUALIFIED has ID of type string, should be int. You may be using a library with broken token emulation error on PHP 7.4

Temporary solution (implemented):

• use PHP 7.2 for coverage collection

Permanent solution:

• use approach from the GH Actions: warm PHPUnit cache on PHPUnit 9.3+ PHPCSStandards/PHP_CodeSniffer#245