Bump the phpstan group with 1 update

Updates the requirements on [shipmonk/phpstan-rules](https://github.com/shipmonk-rnd/phpstan-rules) to permit the latest version.
- [Release notes](https://github.com/shipmonk-rnd/phpstan-rules/releases)
- [Commits](shipmonk-rnd/phpstan-rules@2.9.0...2.9.1)

---
updated-dependencies:
- dependency-name: shipmonk/phpstan-rules
  dependency-type: direct:development
  dependency-group: phpstan
...

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

composer.json

@@ -30,7 +30,7 @@
         "phpstan/phpstan-phpunit": "1.3.14",
         "phpstan/phpstan-strict-rules": "1.5.1",
         "spaze/phpstan-disallowed-calls": "2.16.0",
-        "shipmonk/phpstan-rules": "2.9.0",
+        "shipmonk/phpstan-rules": "2.9.1",
         "phpunit/phpunit": "^8.5.21 || ^9.5.10"
     },
     "autoload": {