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/Plan/AlterTable.php

@@ -0,0 +1,72 @@
+<?php
+
+/**
+ * MIT License
+ * For full license information, please view the LICENSE file that was distributed with this source code.
+ */
+
+namespace Phinx\Db\Plan;
+
+use Phinx\Db\Action\Action;
+use Phinx\Db\Table\Table;
+
+/**
+ * A collection of ALTER actions for a single table
+ */
+class AlterTable
+{
+    /**
+     * The table
+     *
+     * @var \Phinx\Db\Table\Table
+     */
+    protected $table;
+
+    /**
+     * The list of actions to execute
+     *
+     * @var \Phinx\Db\Action\Action[]
+     */
+    protected $actions = [];
+
+    /**
+     * Constructor
+     *
+     * @param \Phinx\Db\Table\Table $table The table to change
+     */
+    public function __construct(Table $table)
+    {
+        $this->table = $table;
+    }
+
+    /**
+     * Adds another action to the collection
+     *
+     * @param \Phinx\Db\Action\Action $action The action to add
+     * @return void
+     */
+    public function addAction(Action $action): void
+    {
+        $this->actions[] = $action;
+    }
+
+    /**
+     * Returns the table associated to this collection
+     *
+     * @return \Phinx\Db\Table\Table
+     */
+    public function getTable(): Table
+    {
+        return $this->table;
+    }
+
+    /**
+     * Returns an array with all collected actions
+     *
+     * @return \Phinx\Db\Action\Action[]
+     */
+    public function getActions(): array
+    {
+        return $this->actions;
+    }
+}