enable cargo sparse protocol

[segfault-magnet]

closes: #886
This should speed up our CI.

Checklist

• I have linked to any relevant issues.
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[segfault-magnet]

Turns out dtolnay/rust-toolchain does this already by checking if the rust version is compatible. So the CI will use the sparse protocol automatically because we've bumped the rust version to 1.68.0.

So, CI-wise, the .cargo/config.toml is not needed. But I'm thinking about whether to remove it because it will apply to anyone building the project locally. But then again we all can just set this config in our $HOME/.cargo/config.toml.

@FuelLabs/sdk-rust thoughts?

[hal3e]

I would not add it. SDK users can set it up locally if they want and it will become a default anyway at some point.

[segfault-magnet]

SDK users can set it up locally if they want

SDK devs *, this doesn't impact users.

I wouldn't add it as well but figured I better ask.

We still need to bump the rust version for it to work in CI though

[segfault-magnet]

Removed the config. Left only the version bump.

[hal3e]

Thanks for this! Please do not forget to update the commit message

[segfault-magnet]

Please do not forget to update the commit message

When have I ever :D