Adding PHPUnit for Test

Author: CodeWithSushil

composer.json

@@ -13,7 +13,8 @@
         "phpstan/phpstan": "^1.12",
         "symfony/polyfill-php80": "^1.31",
         "symfony/polyfill-ctype": "^1.31",
-        "symfony/polyfill-mbstring": "^1.31"
+        "symfony/polyfill-mbstring": "^1.31",
+        "phpunit/phpunit": "^11.4"
     },
     "license": "MIT",
     "autoload": {