Update tests to PHPUnit 11

Summary:
Minimum version of PHP to run tests needs to be bumped to:

• 7.1.O to use void
• 8.0.0 to use attributes
• 8.2.0 to use PHPUnit 11

Ref T2035

Test Plan: composer install && vendor/bin/phpunit tests/

Reviewers: aceppaluni

Reviewed By: aceppaluni

Maniphest Tasks: T2035

Differential Revision: https://devcentral.nasqueron.org/D3528