Update phpunit/phpunit requirement from ^8.0 to ^9.5

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-9.5.md)
- [Commits](sebastianbergmann/phpunit@8.0.0...9.5.4)

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

Signed-off-by: dependabot[bot] <support@github.com>

composer.json

@@ -35,7 +35,7 @@
     ],
     "require-dev": {
         "ext-pdo_sqlite": "*",
-        "phpunit/phpunit": "^8.0",
+        "phpunit/phpunit": "^9.5",
         "ramsey/uuid": "^4.0",
         "broadway/coding-standard": "^1.2",
         "phpstan/phpstan": "@stable"