Update phpunit/phpunit requirement from ^7.5 to ^7.5 || ^8.0
Update phpunit/phpunit requirement from ^7.5 to ^7.5 || ^8.0

Updates the requirements on [phpunit/phpunit](https://github.com/sebastianbergmann/phpunit) to permit the latest version.
- [Release notes](https://github.com/sebastianbergmann/phpunit/releases)
- [Changelog](https://github.com/sebastianbergmann/phpunit/blob/master/ChangeLog-8.0.md)
- [Commits](https://github.com/sebastianbergmann/phpunit/compare/7.5.0...8.0.6)

Signed-off-by: dependabot[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@dependabot.com>
mimmi20/wurfl-generic-request