Update toolchain version.

[ilyalesokhin-starkware]

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[reviewable-StarkWare]

This change is 

[ilyalesokhin-starkware]

crates/prover/src/core/backend/simd/lookups/gkr.rs line 28 at r1 (raw file):

        // Start DP with CPU backend to avoid dealing with instances smaller than a SIMD vector.
        let (y_rem, y_last_chunk) = y.split_last_chunk::<{ LOG_N_LANES as usize }>().unwrap();

this was fun to debug :(

Code quote:

 let (y_rem, y_last_chunk)

[ilyalesokhin-starkware]

crates/prover/src/lib.rs line 14 at r1 (raw file):

    portable_simd,
    slice_ptr_get,
    stdarch_x86_avx512,

is there a way to enable this only if
#[cfg(not(target_arch = "wasm32"))]

Code quote:

stdarch_x86_avx512,