v1.7.3

What's Changed

内部的なリファクタのみです。

• add Update Major Version Tag by @kumackey in #18
• Internal packageに移動 by @kumackey in #19
• Refactor by @kumackey in #20
• RSSClientとして汎用的な設計に変更 by @kumackey in #21

Full Changelog: v1.7.1...v1.7.3