Update phpstan/phpstan requirement from 1.8.11 to 1.9.14 (#82)

Updates the requirements on [phpstan/phpstan](https://github.com/phpstan/phpstan) to permit the latest version.
- [Release notes](https://github.com/phpstan/phpstan/releases)
- [Changelog](https://github.com/phpstan/phpstan/blob/1.10.x/CHANGELOG.md)
- [Commits](phpstan/phpstan@1.8.11...1.9.14)

---
updated-dependencies:
- dependency-name: phpstan/phpstan
  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

@@ -8,7 +8,7 @@
         "php-64bit": "*"
     },
     "require-dev": {
-        "phpstan/phpstan": "1.8.11",
+        "phpstan/phpstan": "1.9.14",
         "phpstan/extension-installer": "^1.0",
         "phpstan/phpstan-strict-rules": "^1.0",
         "phpunit/phpunit": "^8.5 || ^9.5"