Bump phpunit/phpunit from 8.2.3 to 8.3.5 (#16)

Bumps [phpunit/phpunit](https://github.com/sebastianbergmann/phpunit) from 8.2.3 to 8.3.5.
- [Release notes](https://github.com/sebastianbergmann/phpunit/releases)
- [Changelog](https://github.com/sebastianbergmann/phpunit/blob/master/ChangeLog-8.3.md)
- [Commits](sebastianbergmann/phpunit@8.2.3...8.3.5)

Signed-off-by: dependabot-preview[bot] <[email protected]>