feat: commit vendor folder directly to bypass air-gapped build restrictions

vendor/myclabs/php-enum/stubs/Stringable.php

@@ -0,0 +1,11 @@
+<?php
+
+if (\PHP_VERSION_ID < 80000 && !interface_exists('Stringable')) {
+    interface Stringable
+    {
+        /**
+         * @return string
+         */
+        public function __toString();
+    }
+}