build(deps): update rector/rector requirement in /tools

Updates the requirements on [rector/rector](https://github.com/rectorphp/rector) to permit the latest version.
- [Release notes](https://github.com/rectorphp/rector/releases)
- [Commits](rectorphp/rector@2.0.0...2.1.0)

---
updated-dependencies:
- dependency-name: rector/rector
  dependency-version: 2.1.0
  dependency-type: direct:production
...

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

Author: dependabot[bot]

tools/composer.json

@@ -5,7 +5,7 @@
     "phpstan/phpstan": "^2.1",
     "phpstan/phpstan-phpunit": "^2.0",
     "staabm/annotate-pull-request-from-checkstyle": "^1.8",
-    "rector/rector": "^2.0"
+    "rector/rector": "^2.1"
   },
   "config": {
     "allow-plugins": {