feat(cmd.action): bind to $this

Author: adhocore

src/Input/Command.php

@@ -413,7 +413,7 @@ public function action(callable $action = null)
             return $this->_action;
         }
 
-        $this->_action = $action;
+        $this->_action = $action ? \Closure::bind($action, $this) : null;
 
         return $this;
     }