Disable default features for sha3

[Shatur]

The sha3 crate by default enables alloc and oid, which aren't needed. I checked it locally with cargo check -p ml-dsa --all-features. I assume this was just an oversight, since slh-dsa already disables the default features for sha3:

signatures/slh-dsa/Cargo.toml

Line 21 in 8aa41de

sha3 = { version = "0.11.0-rc.0", default-features = false }