build(deps-dev): update rector/rector requirement from 2.6.3 to 2.6.6

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](https://github.com/rectorphp/rector/compare/2.6.3...2.6.6)

---
updated-dependencies:
- dependency-name: rector/rector
  dependency-version: 2.6.6
  dependency-type: direct:development
...

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

composer.json

@@ -35,7 +35,7 @@
         "symfony/phpunit-bridge": "^4.4|^5.3|^6.0|^7.0",
         "phpstan/phpstan": "2.2.12",
         "phpstan/phpstan-phpunit": "2.0.18",
-        "rector/rector": "2.6.3"
+        "rector/rector": "2.6.6"
     },
     "suggest": {
         "ext-tidy": "Used to clean up given HTML and to avoid problems with bad HTML structure."