Update phpstan/phpstan requirement from 1.11.9 to 1.12.0 (#31)

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/1.12.x/CHANGELOG.md)
- [Commits](phpstan/phpstan@1.11.9...1.12.0)

---
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

@@ -24,7 +24,7 @@
 	},
 	"require-dev": {
 		"nette/tester": "~2.0",
-		"phpstan/phpstan": "1.11.9",
+		"phpstan/phpstan": "1.12.0",
 		"phpstan/extension-installer": "1.4.1",
 		"phpstan/phpstan-strict-rules": "1.6.0"
 	},