GH Actions: improve fix to run the tests on PHP 8.1
GH Actions: improve fix to run the tests on PHP 8.1

There is no need to remove the config file and have all settings on the command-line as PHPUnit offers a `--no-configuration` option to ignore the config file.

Enabling that simplifies the action steps a little and isolates the customization for PHP 8.1 to PHP 8.1.

squizlabs/PHP_CodeSniffer,stronk7/PHP_CodeSniffer,jrfnl/PHP_CodeSniffer,jrfnl/PHP_CodeSniffer,jrfnl/PHP_CodeSniffer,squizlabs/PHP_CodeSniffer,stronk7/PHP_CodeSniffer,stronk7/PHP_CodeSniffer,squizlabs/PHP_CodeSniffer