update CHANGELOG.md

Author: KoyanagiHitoshi

CHANGELOG.md

@@ -1,5 +1,10 @@
 # Change Log
 
+## [v3.4.0](https://github.com/KoyanagiHitoshi/AtCoder-Python-Introduction/releases/tag/v3.4.0) / 2023-08-06
+
+* [#25](https://github.com/KoyanagiHitoshi/AtCoder-Python-Introduction/pull/25) update CHANGELOG.md
+* [#25](https://github.com/KoyanagiHitoshi/AtCoder-Python-Introduction/pull/25) add code
+
 ## [v3.3.0](https://github.com/KoyanagiHitoshi/AtCoder-Python-Introduction/releases/tag/v3.3.0) / 2023-07-02
 
 * [#24](https://github.com/KoyanagiHitoshi/AtCoder-Python-Introduction/pull/24) update CHANGELOG.md