Bump phpstan/phpstan from 1.12.33 to 2.1.54 (#46)

---
updated-dependencies:
- dependency-name: phpstan/phpstan
  dependency-version: 2.1.54
  dependency-type: direct:development
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

composer.json

@@ -9,7 +9,7 @@
 		"phpgt/promise": "^2.0"
 	},
 	"require-dev": {
-		"phpstan/phpstan": "^1.10",
+		"phpstan/phpstan": "^2.1",
 		"phpunit/phpunit": "^10.1",
 		"phpmd/phpmd": "^2.13",
 		"squizlabs/php_codesniffer": "^3.7"