fix: set composer to minimum PHP 8.1

Author: ddevsr

composer.json

@@ -4,7 +4,7 @@
     "license": "MIT",
     "description": "Rector upgrades rules for Codeigniter4",
     "require": {
-        "php": ">=8.0",
+        "php": ">=8.1",
         "rector/rector": "^1.0"
     },
     "require-dev": {