Optimize PNG files

[papjul]

Optimize PNG files using oxipng -Z -o max --strip all.
Should make the APK slightly smaller without losing quality.

Note: the icon.png was actually a JPEG. So I replaced it with the other similar PNG file from the drawable directory.

[sakusaku3939]

Thanks for optimizing the images! I didn't know that the fake .png I found in the past were still there...🫠

[sakusaku3939]

LGTM
@papjul Since this change has minimal impact on users, would it be alright to include it in the next irregularly scheduled release?

[papjul]

Yes, it's a minor change ;)

[sakusaku3939]

Thanks! 🚀