Document MSRV as 1.76

[goffrie]

#83 uses inline const which isn't stable until 1.79

[jplatte]

I think it would be good to add it to Cargo.toml as well.

[jneem]

Huh, I don't have any real objection to bumping MSRV, but I'm concerned that we didn't catch this in CI. The CI runs all the tests on 1.51 -- do you know why it didn't catch this?

[goffrie]

I don't think CI is actually running the requested toolchain version, I'm pretty sure it's always running stable.

I tried running cargo test on 1.51 and it already failed trying to build the latest libc (since this repo doesn't have Cargo.lock checked in).

[jplatte]

Looks like you're using the deprecated actions-rs/toolchain@v1. IIRC you have to use its override or default option to actually have the installation affect what cargo commands without +toolchain do. Most Rust GitHub CI workflows have switched to https://github.com/dtolnay/rust-toolchain.

[goffrie]

#94 adds override: true. switching seems like a reasonable idea too.

[goffrie]

#95 should let us lower the msrv to 1.65 at least

[jneem]

After the various other changes, 1.76 is the minimal version (with triomphe as the bottleneck).