fix: 修正由于值引用导致服务 config 被清空问题

Author: Anoxia

src/Kernel/Config.php

@@ -22,10 +22,10 @@ public function get($key, $defaultValue = null)
             return $this->data[$key];
         }
 
-        $point = &$this->data;
+        $point = $this->data;
         foreach (explode('.', $key) as $segment) {
             if (array_key_exists($segment, $point)) {
-                $point = &$point[$segment];
+                $point = $point[$segment];
             } else {
                 $point = [];