Upgraded to Pyxel 1.5.3

Hiya!

The Pyxel development is going fast now! Version 1.5.3 has been released a few days ago. You don’t have to worry: it is safe to use this new version. Actually, we encourage you to keep using the newest versions of our deps, so we can use the latest bug fixes and features!

See the related PR on GitHub: DiddiLeija/diddi-and-the-bugs#4.