Bump phpunit/phpunit from 7.5.1 to 7.5.2 (koel#895)

Bumps [phpunit/phpunit](https://github.com/sebastianbergmann/phpunit) from 7.5.1 to 7.5.2.
<details>
<summary>Changelog</summary>

*Sourced from [phpunit/phpunit's changelog](https://github.com/sebastianbergmann/phpunit/blob/master/ChangeLog-7.5.md).*

> ## [7.5.2] - 2019-01-15
> 
> ### Fixed
> 
> * Fixed [#3456](https://github-redirect.dependabot.com/sebastianbergmann/phpunit/pull/3456): Generator for Xdebug filter script does not handle directories with leading `.` correctly
> * Fixed [#3459](https://github-redirect.dependabot.com/sebastianbergmann/phpunit/issues/3459): `[**requires**](https://github.com/requires)` function swallows digits at the end of function name
</details>
<details>
<summary>Commits</summary>

- [`7c89093`](sebastianbergmann/phpunit@7c89093) Prepare release
- [`6bef716`](sebastianbergmann/phpunit@6bef716) Merge branch '6.5' into 7.5
- [`6050504`](sebastianbergmann/phpunit@6050504) Bump copyright year
- [`99bd534`](sebastianbergmann/phpunit@99bd534) Fix CS/WS issue
- [`56e1bce`](sebastianbergmann/phpunit@56e1bce) Update ChangeLog
- [`afa7f01`](sebastianbergmann/phpunit@afa7f01) feat(xdebug-filter-generator): improve directories paths
- [`be5f758`](sebastianbergmann/phpunit@be5f758) Merge branch '6.5' into 7.5
- [`a33f8d2`](sebastianbergmann/phpunit@a33f8d2) Update php-cs-fixer
- [`eb22621`](sebastianbergmann/phpunit@eb22621) Revert "Do not use Phive to manage php-cs-fixer (for now)"
- [`d44f244`](sebastianbergmann/phpunit@d44f244) Merge branch '6.5' into 7.5
- Additional commits viewable in [compare view](sebastianbergmann/phpunit@7.5.1...7.5.2)
</details>
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