TASK: Add platform requirement to composer.json

Author: grebaldi

composer.json

@@ -15,6 +15,9 @@
         "analyse": "phpstan analyse --level 8 src tests",
         "test": "phpunit --enforce-time-limit --bootstrap vendor/autoload.php --testdox tests --coverage-html build/coverage-report --whitelist src"
     },
+    "require": {
+        "php": ">=8.1"
+    },
     "require-dev": {
         "phpunit/phpunit": "^9.5",
         "phpstan/phpstan": "^1.9",