修复seeder错误；删除第三方的think迁移工具，在extend中重新实现；

extend/phinx/Db/Action/ChangeComment.php

@@ -0,0 +1,42 @@
+<?php
+
+/**
+ * MIT License
+ * For full license information, please view the LICENSE file that was distributed with this source code.
+ */
+
+namespace Phinx\Db\Action;
+
+use Phinx\Db\Table\Table;
+
+class ChangeComment extends Action
+{
+    /**
+     * The new comment for the table
+     *
+     * @var string|null
+     */
+    protected $newComment;
+
+    /**
+     * Constructor
+     *
+     * @param \Phinx\Db\Table\Table $table The table to be changed
+     * @param string|null $newComment The new comment for the table
+     */
+    public function __construct(Table $table, ?string $newComment)
+    {
+        parent::__construct($table);
+        $this->newComment = $newComment;
+    }
+
+    /**
+     * Return the new comment for the table
+     *
+     * @return string|null
+     */
+    public function getNewComment(): ?string
+    {
+        return $this->newComment;
+    }
+}