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/RemoveColumn.php

@@ -0,0 +1,59 @@
+<?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\Column;
+use Phinx\Db\Table\Table;
+
+class RemoveColumn extends Action
+{
+    /**
+     * The column to be removed
+     *
+     * @var \Phinx\Db\Table\Column
+     */
+    protected $column;
+
+    /**
+     * Constructor
+     *
+     * @param \Phinx\Db\Table\Table $table The table where the column is
+     * @param \Phinx\Db\Table\Column $column The column to be removed
+     */
+    public function __construct(Table $table, Column $column)
+    {
+        parent::__construct($table);
+        $this->column = $column;
+    }
+
+    /**
+     * Creates a new RemoveColumn object after assembling the
+     * passed arguments.
+     *
+     * @param \Phinx\Db\Table\Table $table The table where the column is
+     * @param string $columnName The name of the column to drop
+     * @return static
+     */
+    public static function build(Table $table, string $columnName)
+    {
+        $column = new Column();
+        $column->setName($columnName);
+
+        return new static($table, $column);
+    }
+
+    /**
+     * Returns the column to be dropped
+     *
+     * @return \Phinx\Db\Table\Column
+     */
+    public function getColumn(): Column
+    {
+        return $this->column;
+    }
+}