Update rector/rector requirement from 0.18.2 to 0.18.4

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@0.18.2...0.18.4)

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

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

Author: dependabot[bot]

composer.json

@@ -18,7 +18,7 @@
     "require-dev": {
         "codeigniter4/devkit": "^1.0",
         "codeigniter4/framework": "^4.4",
-        "rector/rector": "0.18.2"
+        "rector/rector": "0.18.4"
     },
     "minimum-stability": "dev",
     "prefer-stable": true,