Update phpunit/phpunit requirement from ^10.3.2 to ^10.3.4 (#86)

Updates the requirements on [phpunit/phpunit](https://github.com/sebastianbergmann/phpunit) to permit the latest version.
- [Changelog](https://github.com/sebastianbergmann/phpunit/blob/10.3.4/ChangeLog-10.3.md)
- [Commits](sebastianbergmann/phpunit@10.3.2...10.3.4)

---
updated-dependencies:
- dependency-name: phpunit/phpunit
  dependency-type: direct:development
...

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Author: dependabot[bot]

composer.json

@@ -17,7 +17,7 @@
   },
   "require-dev": {
     "doctrine/coding-standard": "^12.0",
-    "phpunit/phpunit": "^10.3.2",
+    "phpunit/phpunit": "^10.3.4",
     "psalm/plugin-phpunit": "^0.18.4",
     "vimeo/psalm": "^5.15"
   },