chore(deps-dev): update phpstan/phpstan requirement

---
updated-dependencies:
- dependency-name: phpstan/phpstan
  dependency-version: 2.1.31
  dependency-type: direct:development
...

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

Author: dependabot[bot]

composer.json

@@ -15,7 +15,7 @@
         "php": "^8.4"
     },
     "require-dev": {
-        "phpstan/phpstan": "2.1.29",
+        "phpstan/phpstan": "2.1.31",
         "phpunit/phpunit": "12.3.15",
         "friendsofphp/php-cs-fixer": "3.88.2"
     },