Update phpstan/phpstan-phpunit requirement from ^1.3.15 to ^1.3.16

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@1.3.15...1.3.16)

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

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

Author: dependabot[bot]

composer.json

@@ -14,7 +14,7 @@
         "editorconfig-checker/editorconfig-checker": "^10.5.0",
         "ergebnis/composer-normalize": "^2.30.2",
         "phpstan/phpstan": "^1.10.13",
-        "phpstan/phpstan-phpunit": "^1.3.15",
+        "phpstan/phpstan-phpunit": "^1.3.16",
         "phpstan/phpstan-strict-rules": "^1.5.2",
         "phpunit/phpunit": "^10.1",
         "shipmonk/composer-dependency-analyser": "^1.2",