Update embedded-graphics to 0.8.0

[andber1]

The RgbColor trait has changed in embedded-graphics. So this change is needed if you want to use the latest embedded-graphics crate.
I am not sure how to fix the errors in the GitHub workflows. I have seen those errors before my changes as well.

[LuckyTurtleDev]

The errors sound liken an breaking change at rust !?!
The last commit can not be test with the current rust version, but the old CI run had no issue as it had run with now old rust. However rerunning it cause exactly the same issue as them I have local now.

Luckily this was an easy fix:

- //! const IMAGE: Image\<Bgr565> = "grass.png";
+ //! const IMAGE: Image\<Bgr565> = "embedded-sprites/grass.png";