Bump embassy-sync from 0.7.2 to 0.8.0

[bramsdell-ms]

Update embassy-sync dependency to version 0.8.0 to align with workspaces that have moved to the latest embassy ecosystem. No API changes required - RawMutex, Mutex, Signal all retain the same interface.

I have a corresponding PR for embedded-services

[github-actions]

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[kurtjd]

v0.8.0 of embassy-sync doesn't appear to be published on crates.io yet, so this PR can't really be merged until that is the case.

[asasine]

Need to update the lock file too.

[jerrysxie]

v0.8.0 of embassy-sync doesn't appear to be published on crates.io yet, so this PR can't really be merged until that is the case.

On the embassy matrix chat, it seems like the embassy team is still waiting on an executor change before release 0.8.0. So we might want to hold off until that happen to do a full upgrade: https://matrix.to/#/!YoLPkieCYHGzdjUhOK:matrix.org/$WEtwQawscVmxg6xzNj0iN68Nm5qwrSPpl_PRisM8WbE?via=matrix.org&via=mozilla.org&via=beeper.com