composer(deps-dev): update phpunit/phpunit requirement

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@9.5.3...9.5.4)

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

Author: dependabot[bot]

composer.json

@@ -32,7 +32,7 @@
         "mikey179/vfsstream": "^1.6",
         "mockery/mockery": "^1.4",
         "orchestra/testbench": "^6.15.0",
-        "phpunit/phpunit": "^9.5.3"
+        "phpunit/phpunit": "^9.5.4"
     },
     "config": {
         "sort-packages": true