Update phpstan/phpstan requirement in the composer group

Updates the requirements on [phpstan/phpstan](https://github.com/phpstan/phpstan) to permit the latest version.

Updates `phpstan/phpstan` to 1.12.0
- [Release notes](https://github.com/phpstan/phpstan/releases)
- [Changelog](https://github.com/phpstan/phpstan/blob/1.12.x/CHANGELOG.md)
- [Commits](phpstan/phpstan@1.11.11...1.12.0)

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

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

composer.json

@@ -33,7 +33,7 @@
         "friendsofphp/php-cs-fixer": "^2.19||^3.40",
         "masterminds/html5": "^2.8",
         "phpstan/extension-installer": "^1.0",
-        "phpstan/phpstan": "1.11.11",
+        "phpstan/phpstan": "1.12.0",
         "phpstan/phpstan-phpunit": "1.4.0",
         "phpstan/phpstan-symfony": "1.4.8",
         "phpunit/phpunit": "^8.5.14||^9.3.9",