add migration to drop preferences column

migrations/2019_07_09_212000_change_users_drop_preferences.php

@@ -0,0 +1,27 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * (c) Toby Zerner <toby.zerner@gmail.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Database\Schema\Builder;
+
+return [
+    'up' => function (Builder $schema) {
+        $schema->table('posts', function (Blueprint $table) {
+            $table->dropColumn('preferences');
+        });
+    },
+
+    'down' => function (Builder $schema) {
+        $schema->table('posts', function (Blueprint $table) {
+            $table->binary('preferences')->nullable();
+        });
+    }
+];