build(deps-dev): update phpstan/extension-installer requirement

Updates the requirements on [phpstan/extension-installer](https://github.com/phpstan/extension-installer) to permit the latest version.
- [Release notes](https://github.com/phpstan/extension-installer/releases)
- [Commits](phpstan/extension-installer@1.1.0...1.2.0)

---
updated-dependencies:
- dependency-name: phpstan/extension-installer
  dependency-type: direct:development
...

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

composer.json

@@ -35,7 +35,7 @@
 		"nette/tester": "~2.3",
 		"marc-mabe/php-enum": "~3.0",
 		"mockery/mockery": "~1.2",
-		"phpstan/extension-installer": "1.1.0",
+		"phpstan/extension-installer": "1.2.0",
 		"phpstan/phpstan": "1.8.0",
 		"phpstan/phpstan-deprecation-rules": "1.0.0",
 		"phpstan/phpstan-nette": "1.0.0",