Update dependency psalm/plugin-phpunit to ^0.18

[renovate[bot]]

This PR contains the following updates:

Package	Type	Update	Change
psalm/plugin-phpunit	require-dev	minor	^0.17 -> ^0.18

---

Release Notes

psalm/psalm-plugin-phpunit

### [`v0.18.0`](https://togithub.com/psalm/psalm-plugin-phpunit/releases/tag/0.18.0) [Compare Source](https://togithub.com/psalm/psalm-plugin-phpunit/compare/0.17.0...0.18.0) #### What's Changed - \[composer.json] allow Psalm 5 beta by [@​someniatko](https://togithub.com/someniatko) in [https://github.com/psalm/psalm-plugin-phpunit/pull/122](https://togithub.com/psalm/psalm-plugin-phpunit/pull/122) - Immutable refactoring by [@​danog](https://togithub.com/danog) in [https://github.com/psalm/psalm-plugin-phpunit/pull/123](https://togithub.com/psalm/psalm-plugin-phpunit/pull/123) #### New Contributors - [@​someniatko](https://togithub.com/someniatko) made their first contribution in [https://github.com/psalm/psalm-plugin-phpunit/pull/122](https://togithub.com/psalm/psalm-plugin-phpunit/pull/122) - [@​danog](https://togithub.com/danog) made their first contribution in [https://github.com/psalm/psalm-plugin-phpunit/pull/123](https://togithub.com/psalm/psalm-plugin-phpunit/pull/123) **Full Changelog**: https://github.com/psalm/psalm-plugin-phpunit/compare/0.17.0...0.18.0

---

Configuration

📅 Schedule: Branch creation - At any time (no schedule defined), Automerge - At any time (no schedule defined).

🚦 Automerge: Disabled by config. Please merge this manually once you are satisfied.

♻ Rebasing: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox.

🔕 Ignore: Close this PR and you won't be reminded about this update again.

---

• [ ] If you want to rebase/retry this PR, check this box

---

This PR has been generated by Mend Renovate. View repository job log here.