edgebadge: update embedded-graphics to 0.8

[LuckyTurtleDev]

Summary

fix #724

Checklist

• CHANGELOG.md for the BSP or HAL updated
• All new or modified code is well documented, especially public items
• No new warnings or clippy suggestions have been introduced - CI will deny clippy warnings by default! You may #[allow] certain lints where reasonable, but ideally justify those with a short comment.

[jbeaurivage]

Thanks @LuckyTurtleDev, two minor comments and I'll be happy to merge:

• Please leave the edgebadge crate version as is. We take care of bumping it during the release process.
• Please update the edgebadge README with the changes under the # Unreleased section.

[LuckyTurtleDev]

I currently have no access to an edgebadge/pybadge for testing.

[LuckyTurtleDev]

Thanks @LuckyTurtleDev, two minor comments and I'll be happy to merge:

* Please leave the edgebadge crate version as is. We take care of bumping it during the release process.

* Please update the edgebadge README with the changes under the `# Unreleased` section.

finish