Update rector/rector requirement from ^1.2.3 to ^1.2.4 (#658)

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@1.2.3...1.2.4)

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

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

Author: dependabot[bot]

composer.json

@@ -33,7 +33,7 @@
         "phpstan/phpstan": "^1.11.11",
         "phpstan/phpstan-phpunit": "^1.4.0",
         "phpunit/phpunit": "^8.5.38",
-        "rector/rector": "^1.2.3"
+        "rector/rector": "^1.2.4"
     },
     "suggest": {
         "ext-mbstring": "for parsing UTF-8 CSS"