PostgreSQLにはAFTERの機能がないっぽいのでハマった。
https://wiki.postgresql.org/wiki/Alter_column_position/ja
https://tikkss.hatenablog.jp/entry/2015/04/13/185918
https://api.rubyonrails.org/classes/ActiveRecord/ConnectionAdapters/PostgreSQL/SchemaStatements.html#method-i-add_column
https://qiita.com/hondy12345/items/59a2a2686a78b13b80e0