Update phpunit/phpunit requirement from ^9.2 to ^9.3

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-9.3.md)
- [Commits](sebastianbergmann/phpunit@9.2.0...9.3.0)

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

composer.json

@@ -34,7 +34,7 @@
         "phpstan/phpstan-phpunit": "^0.12",
         "phpstan/phpstan-strict-rules": "^0.12",
         "phpunit/php-invoker": "^3.0",
-        "phpunit/phpunit": "^9.2",
+        "phpunit/phpunit": "^9.3",
         "squizlabs/php_codesniffer": "^3.5"
     },
     "autoload": {