[TASK] Update phpstan/phpstan-phpunit requirement from ^1.3.16 to ^1.…

…4.0 (#60)

Updates the requirements on [phpstan/phpstan-phpunit](https://github.com/phpstan/phpstan-phpunit) to permit the latest version.
- [Release notes](https://github.com/phpstan/phpstan-phpunit/releases)
- [Commits](phpstan/phpstan-phpunit@1.3.16...1.4.0)

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

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

composer.json

@@ -23,7 +23,7 @@
         "phpstan/extension-installer": "^1.4.1",
         "phpstan/phpstan": "^1.11.6",
         "phpstan/phpstan-deprecation-rules": "^1.2",
-        "phpstan/phpstan-phpunit": "^1.3.16",
+        "phpstan/phpstan-phpunit": "^1.4.0",
         "phpstan/phpstan-strict-rules": "^1.6.0",
         "phpunit/phpunit": "^10.5.24",
         "rector/rector": "^1.2.0",