Add typehint return to support phpunit 8.0

[williamdes]

sql-parser/tests/Lexer/TokensListTest.php

Line 22 in 69ee110

public function setUp()

Made the CI fail on https://salsa.debian.org/phpmyadmin-team/sql-parser/-/jobs/336960

[williamdes]

Only on master branch since typehint support for : void starts in https://www.php.net/manual/en/migration71.new-features.php