chore: Reduce MSRV

[hashcashier]

is_none_or is stable as of Rust 1.82, while the RISC Zero zkvm toolchain is currently using 1.81

This patch introduces more verbose code to bring the MSRV back down to 1.81 to avoid compiling with unstable features.

Generally it would also be great if Kona could have an MSRV policy set (e.g. MSRV is always at least 2 versions behind) to help avoid these issues.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.6%. Comparing base (8f21eff) to head (d39b314).
Report is 1 commits behind head on main.

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[clabby]

This lgtm, but also should decrement the rust-version in the workspace's Cargo.toml.

[samlaf]

@hashcashier can you make the requested change so we can get this merged? Currently need to point to your repo when integrating with Kailua, would love to get rid of dependency hell by having this merged.

Seems like you'll need to revert the changes in #859 to bring down the MSRV to 1.81, and potentially add some comments or use nightly version to shutup some lint warnings.

[hashcashier]

Sorry I'd lost track of this. Should be good to go now.

[samlaf]

@clabby can we merge this?

[clabby]

@clabby can we merge this?

Yeah, apologies for the long turnaround. On vacation atm.

[samlaf]

@clabby figured! Thanks for merging this, enjoy your break haha.